The work and pensions secretary has criticised people "who think they're too good" to stack supermarket shelves on back-to-work government schemes.
On the BBC's Andrew Marr Show, Iain Duncan Smith suggested that many "smart people" overlooked the importance of effective shelf-stacking.
A geology graduate recently won a legal victory over the back-to-work scheme.
But Mr Duncan Smith warned against assuming that geology was more important than supermarket work.
Geology graduate Cait Reilly, 24, argued at the Appeal Court that her unpaid work placement at Poundland, which she had been required to undertake in return for continued benefits payments, breached laws on forced labour.
'Most successful' scheme
Although Miss Reilly won the case, Mr Duncan Smith said the judges had decided her argument that the scheme breached her human rights was "rubbish".
The court had ruled against the government, he explained, because "the regulations were set too wide and weren't specific enough".
"I've already put emergency regulations down, and that's ended it," he added.
Commenting further on the case, Mr Duncan Smith said: "I understand she said she wasn't paid. She was paid jobseeker's allowance, by the taxpayer, to do this.
"I'm sorry, but there is a group of people out there who think they're too good for this kind of stuff.
"Let me remind you that [former Tesco chief executive] Terry Leahy started his life stacking shelves.
"The next time somebody goes in - those smart people who say there's something wrong with this - they go into their supermarket, ask themselves this simple question, when they can't find the food they want on the shelves, who is more important - them, the geologist, or the person who stacked the shelves?"
Mr Duncan Smith argued that "most young people love" their work experience placements.
It was the government's "most successful" back-to-work scheme, he said: "It's been so successful that over half of those kids have left benefits."
The scheme had been launched to help young people trapped in a vicious circle where they could not get a job because they did not have any experience on their CVs, he said.
'Complete waste of time'
Mr Duncan Smith added: "But what we've said to them is: once you commit to doing that programme, because companies have to make arrangements around it, then if you don't do this you may suffer a benefit withdrawal because you have messed them around and they are therefore going to suffer as a result of that.
"It's a point that anyone out there listening to this will know. You have to learn early that if you commit to something, you stay and do it."
Miss Reilly, a University of Birmingham geology graduate, and 40-year-old unemployed HGV driver Jamie Wilson, from Nottingham, both succeeded in their claims that the unpaid schemes were legally flawed.
This was because the regulations behind the schemes did not comply with the Act of Parliament that gave the DWP the power to introduce the programme.
Miss Reilly said that in November 2011 she had to leave her voluntary work at a local museum and work unpaid at the Poundland store in Kings Heath, Birmingham, under a scheme known as the "sector-based work academy".
"Those two weeks were a complete waste of my time, as the experience did not help me get a job," she said, after the court ruling on 12 February.
"I was not given any training and I was left with no time to do my voluntary work or search for other jobs.
"The only beneficiary was Poundland, a multi-million pound company. Later I found out that I should never have been told the placement was compulsory.
"I don't think I am above working in shops like Poundland. I now work part-time in a supermarket. It is just that I expect to get paid for working."
In a wide-ranging interview, Mr Duncan Smith also said:
- The UK faces a "big battle" in the EU institutions over rules governing access to benefits, accusing EU officials of trying to "take control" of policies previously left to member states.
- Labour's attempts to characterise planned housing benefit changes as a "bedroom tax" were "nonsense". He added: "We have in social sector housing a very large number of people in houses where they have many more bedrooms than they actually need."