Check out these supermarket prices...

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They're very clever. In fact, you really will be amazed at the cheek of these offers. And by how common they are. Here's a couple from Tesco:

Comfort fabric softeners: Until the 22nd you can get two for just £3.00.

How much are they each? £1.50 Right, so two of them were always going to be £3 weren't they?

Here's another Tesco offer:

Nescafe Original - Special price for 400 grams for £4.79.

But the 100 gram jar only costs two pounds. So it'd be cheaper to buy two of them than the bigger jar.

And what about this little Asda delight:

Buy 2 Asda donuts for just one pound.

Seeing as they're individually priced at 50p, that means you'll save precisely... nothing.

Okay, labels like these are confusing. But are they misleading? If you look closely - these supermarket multibuys don't actually claim to be offering price cuts. It's just that when we see terms like 'special purchase' or 'trial price', we expect them to be cheaper.

But there are other supermarket offers that don't rely on the power of suggestion. These are the ones that really do claim to save you money. And this is where it starts to get really naughty...

Take the Sainsbury Kellogg's Crunchy nut cornflakes packets we spotted. The 'Best Value' pack - well, you've guessed it - wasn't the best value at the time we were looking. In fact, it worked out at £3.49 a kilogram. More expensive than the smaller, simple value pack which worked out at just £2.67 a kilogram.

Asda's also at it with Quaker Oats. Their 'Bigger Pack Better Value' box of 20 sachets works out at 14p a sachet. That's dearer than the smaller pack, which gives you sachets for just 13p each.

Are they allowed to do this? We asked litigation lawyer Andy Millmore:

"When you look at claims that look as though they're objective - like best value better value, biggest box best value - those sort of claims, then the consumer's entitled to know that those claims are actually true. And if you deconstruct them and find that, in fact, it's not the best value, then they're misleading and arguably that's a breach of the regulations."

We also asked some members of the public what they thought:

"I think it's pretty deceiving in that way. Normally when I walk into a supermarket - and I do see best value or value or greater value - I would usually go for that product".

"That pricing is outrageous! Because it really is deceptive!"

"I don't trust any of the supermarkets, I always read the packet."

So how does the biggest supermarket, Tesco, explain such misleading offers?

Well, one Watchdog viewer called them to complain that their 'Better Value' pack of ten Alpen bars was actually more expensive than buying two ordinary packs of five. He got this voicemail:

"The general rule is bigger packs are less expensive. However, the retail industry is seriously competitive currently and this means that the usual rules don't apply. We are working to manage costs as best we can and pass good deals on to customers."

You may think you've seen it all now. Well, so did we. Until we started checking out Asda - and their famous price rollbacks. The meaning couldn't be clearer, could it? A rollback is a price cut. We asked a few members of the public what they thought:

"Roll back is Asda reducing prices each week."

"They roll back the prices to a lower price from previous times."

"Reducing the price - just making it roll back!"

So, why do we keep finding what we can only describe as 'rollbacks in reverse'? Offers where the new price is actually higher than the old one? On one day alone in January, we found 23 online examples, including:

Coke multipack, was £3.00 - rolled back to £3.75.

Kellogg's Special K - Oats & Honey: Was £2.07 - rolled back to £2.99.

Fruit shooters: Was £2.76 - rolled back to £2.89.

Andy Millmore warns,

"You'll start from the assumption that prices come down - it's only if you spend a bit of time looking that you see in fact the price has gone up. The regulations assume you'll be fairly careful and fairly observant, but you may not have time and it may leave a misleading impression on you."

So if you're shopping at Asda - or any of the other supermarkets we've mentioned - then beware: When it comes to tempting offers, things may not always be what they seem...

Tesco have told us:

"Our policy is absolutely to make sure that big packs offer better value and it is never our intention to feature promotions that do not offer real savings. With over 40,000 products and thousands of promotions, we do however occasionally make mistakes. When this happens, as it has here, we put it right and we are sorry. "

In addition, Tesco told us:

"It wasn't right to say the normal rules don't apply. Our colleague had in mind the fact that the market is very competitive at present, with lots of promotions and offers. As we've explained, this means we do make mistakes from time to time and we're sorry. We are committed to offering our customers transparent pricing and genuine promotions."

An Asda spokesperson told Watchdog:

"Customers trust us to always have the lowest prices week in week out, so when we get things wrong like this we're the first to put our hands up and take it on the chin.

"You've highlighted a glitch in our online system which thankfully now we've put right. The bug meant that the rollback flag stayed online for up to 24 hours after the price of certain products had moved back up - which clearly shouldn't happen.

"The store examples you have given are as a result of us continuously moving prices down to make sure we're offering our customers the best possible prices, meaning that sometimes our bigger packs fall out of line.

"The other examples you've highlighted (e.g. doughnuts for 50p - two for £1) are because the store you visited did not remove the multibuy ticket when the price of doughnuts was reduced from 60p to 50p.

"We've re-briefed all our stores to be more vigilant in the future. We'd like to apologise for these silly mistakes.

"We promise to be at least ten per cent cheaper than all our major rivals each time they shop with us and use the Asda Price Guarantee, or we'll refund the difference."

A spokesperson from Sainsbury's told us:

"Sainsbury's is committed to helping customers get the best value possible whether they buy large or smaller products in our stores. In both these cases the smaller packs were on special offer for a short period of time and this meant that they were temporarily better value. We apologise to our customers for any confusion this may have caused."

A Morrisons spokesperson said.

"The term 'Mega Value' is one used by the brand Finish on the 56 pack size; it isn't a term Morrisons has applied to the product. On 16th March the Finish 42 pack was on special offer making it unusually cheaper than the Finish Mega Value 56 pack. The Finish Mega Value 56 pack provides better value for money, when special offers aren't running.

"We display product unit prices on our shelf edge label, allowing customers to make direct comparisons between various sizes of pack. We strive to offer our customers the best value for money at all times.

"We are renowned for our great value, including thousands of price cuts across the essential weekly shop and 'half price and better deals' to deliver great savings on a wide range of items, offering our customers exceptional value."

Watchdog Viewers' Responses:

A couple of weeks ago I bought a cucumber from tesco's online grocery service, it was 80p, but the website was doing it's best to get me to buy 2 for £2 as that was a Special Purchase. Ridiculous!

Clair, Norfolk

Never found this a problem, as i always read the label on the shelf which clearly states the price per 100g, per kg, etc. I was brought up to compare prices per unit measurement to work out the cheapest way to buy!

Johnson, Northampton

What winds me up is Sainsbury's pricing of fruit & veg.
Prices for the same stuff, but packed differently are either "Per Pack" "Per Unit" or per KG. It's a nightmare working out which is cheapest

Ian McIntyre, Wakefield

Not quite the same as roll back etc or better value packs but something I would like to share. Tesco at the moment have Easter bits in stock- make own card kit, pencil toppers etc on sale at £1.50 each 3 for 2. The self same items were indeed on the shelf 4 days ago at 36p and 17p respectively. A rise just in time for Easter holidays. I think that is a right rip off personally!

Anonymous Watchdog Viewer

Tesco - i bought an easter egg online it said £4, but then it said i missed an offer starting tomorrow 2 for £8 then when my delivery had came they had charged me £6 for the easter egg so they had raised the price to think you were saving money, so i emailed them immediately and they refunded the £2

Anonymous Watchdog Viewer

My local Tesco is selling fourpacks of lager for £4.36 each ... or two for £10. Yep, the second one actually costs you £5.64. I declined this tempting offer!

David Ferguson

I've come to accept that supermarkets can mislead in price. My simple advice to viewers, who such as myself may be on a constrained student budget, is to sharpen up on their mental arithmetic or carry a calculator to avoid being caught out.

Alex

How about getting charged more per product if you buy more??!!

For at least 3 weeks, Tescos have been offering Copella fruit juice for £1.72 each or £5.50 for 3. - ie more expensive. I pointed it out twice to staff there but its still on "offer"

Dominic Gillespie