On paper, at least, a collaboration always makes sense. Sometimes they're ways of melding genres to create spectacular new results, as happened with Run‐D.M.C. and Aerosmith's Walk This Way in 1986, and they can work commercially too, combining two fanbases to create monster hits, like Taylor Swift's Bad Blood, which featured Kendrick Lamar.
But not always. Occasionally, things can go awry...
Lou Reed and Metallica
Lou Reed and Metallica first performed together in 2009 at the Rock and Roll Hall of Fame's 25th Anniversary Concert, enjoyed the experience, and decided to record an album together. It didn't seem like a particularly controversial idea - a metal band going head-to-head with a legendary New York songwriter who had released plenty of heavy records in his long career - but it's hard to think of an album that's come out this decade that's been quite so polarising, or caused such an uproar.
Lulu, which was released in 2011, was based on two works by German playwright Frank Wedekind and had an experimental, avant-garde feel, not unlike previous Lou albums (1973's Berlin, for example, or Metal Machine Music from 1975), but quite unlike anything Metallica had recorded before. So, while Lou fans - including David Bowie, who told Lou's widow Laurie Anderson that it was his "his masterpiece" and "his greatest work" - largely took it in their stride, Metallica's didn't. Drummer Lars Ulrich told Spin that the reaction "was more spiteful than anyone was prepared for".
The critics had a field day, too. Pitchfork trashed the album and metal site Blabbermouth said, "Lulu is a catastrophic failure on almost every level," forcing Lou to take a swipe at his detractors in a Telegraph interview. "This is for people who are literate," he said, but Lulu did have fans - in the press, and elsewhere. Perhaps Bowie was right when he told Laurie Anderson, "It will take everyone a while to catch up."
Paul McCartney and Stevie Wonder
Two of the world's greatest musicians combine forces to record a song about racial harmony - what could possibly go wrong? Absolutely nothing. At first. When Ebony and Ivory was released in 1982, it sold in shoals - charging up the charts to No.1 in both the UK and US, and, come 2013, it was ranked by Billboard as being the 69th best-selling song of all time.
The song does, however, have another No.1 to its name. In 2007, it was voted the worst musical collaboration in history by 6 Music listeners, and it's not survived the test of time in America, either. In a list of the 50 worst songs of all time, Blender magazine placed it at No.10.
Undeterred, Macca and Stevie recorded another song together in 2012, Only Our Hearts, which was included on Paul's Kisses on the Bottom album. Because, frankly, they're Paul McCartney and Stevie Wonder and they can do what they want.
Bunny Wailer and Snoop Lion
You've got to hand it to Snoop - if he senses a chance to expand his fanbase in parts of the world where he might be less well-known than he is in the US, he's going to take his chances. As such, it was no surprise that he collaborated with superstar Bollywood actor Akshay Kumar on the title track for 2008 action comedy film, Singh is Kinng (wearing a turban in the video), nor that he was the first to land a feature on a PSY record after the viral success of Gangnam Style (2014's Hangover).
But not all of Snoop's globetrotting hook-ups go to plan. According to the Times of India, the video he shot for a song, King, that he recorded with Iranian-born pop singer Amitis deeply offended the Parsi Zoroastrian community in Kolkata, who filed - unsuccessfully - a civic complaint in court to have it banned. And then there was Snoop's ding-dong with Bunny Wailer during the former's brief outing as Snoop Lion.
The two met in Jamaica in 2012 when Snoop was making an album and film, both called Reincarnated, about his supposed conversion to Rastafarianism. Bunny recorded parts for the record, but they fell out and he later accused Snoop of "outright fraudulent use of Rastafari Community's personalities and symbolism", as well as failing to meet "contractual, moral and verbal commitments". Snoop hit back in Rolling Stone, saying, "You wasn't the s*** in The Wailers. You was just one of them: Bob, Peter Tosh, then you," adding, "The reason for him not being on the album is I started hearing negative energy and rather than have him be a part of it, I kept him in the movie to show his positivity against his negativity."
By the time Snoop's next album came out, 2015's Bush, he was back to being called plain old Snoop Dogg again.
Cher and Gregg Allman
Never work with children or animals, the old adage goes, to which you might also add "or your new spouse", judging by the experiences of Cher and rocker Gregg Allman from The Allman Brothers Band. They married in 1975 and, as - bizarrely - Allman and Woman, released an album together two years later, Two the Hard Way. It wasn't very good. In fact, it was so bad that the 1979 Rolling Stone Record Guide said, "It's hard to imagine a more inappropriate combination... It's the bottom of the barrel after a long fall for Gregg, and more of the same for Cher."
They were, nonetheless, huge stars, so they took the record out on the road on a now-fabled tour, which lost money from the start. Worse was to come. According to Lawrence J. Quirk's 1991 book, Totally Uninhibited: The Life and Wild Times of Cher, Gregg, who had been sober before the tour began, starting drinking again, causing a rift between him and his new wife. By the time the short tour of just 16 dates was completed, their relationship was over and their album - owned by Cher - buried. It's never been released on CD and you also won't find it on streaming services.
Ozzy Osbourne and Miss Piggy
Tricky one. On the one hand, there's nothing wrong with a rock star father to then-young children doing a song squarely aimed at kids; on the other hand, as Ozzy Osbourne told Esquire about his 1994 collaboration with Miss Piggy, "You know, you gotta be careful about what you do... Sometimes it works out okay, but I only do these things for a goof. I mean, believe me: I'm not a big Miss F****** Piggy fan!"
The track they did together - a cover of Steppenwolf's Born to Be Wild - was part of a Muppets spin-off album, Kermit Unpigged, which also featured collaborations with the likes of Don Henley, Jimmy Buffet and George Benson. It was hardly a big hit - it scraped into the Top 20 on Billboard's kids' chart - and did little for Ozzy's reputation among his base, who were already worried that perhaps the Prince of Darkness wasn't quite so dark after all. In 1991, the former Black Sabbath frontman had had a hit with the ballad Mama I'm Coming Home and he was supposed to be retired when the Miss Piggy song came out. The year before he'd released Live & Loud - his final album, he claimed - so was Born to Be Wild a comeback? His swansong? Not surprisingly, Ozzy hit the studio again in 1995, released Ozzmosis, and set out on the road, dubbing his tour 'The Retirement Sucks Tour'.
Ozzy later made peace with his Miss Piggy song, including it on the third CD of a 2005 boxset, Prince of Darkness, along with many other collaborations he'd recorded over the years, including a truly awful cover of the Bee Gees' Stayin' Alive with Frank Zappa's son Dweezil.
Brad Paisley and LL Cool J
And, finally, one of the oddest songs in recent memory - 2013's Accidental Racist, by country star Brad Paisley, featuring old-school rapper LL Cool J. Their intentions might have been good, but the track was met with a universal, "What the heck!?" In a piece titled, Brad Paisley's Accidental Racist: LL Cool J's 10 Craziest Lyrics, Billboard managed, "Paisley's latest track fails to become more than a flat-footed apology for hate-induced uneasiness," and that was one of the kinder comments. Comedians got to work in a series of parodies, including on Saturday Night Live.