This one time, Gruff Rhys was telling me about the time Coca Cola was trying to buy 'Hello Sunshine' to use in an advert. The band, hardly rich, mortgages to pay and babies on the way, kept saying no. Coca Cola kept coming back, zero stacking on top of zero, until there six of those terrible things, and the band nearly split up.

They never gave in though. Those death squads meant more than those zeroes. An admirable attitude, but one that's increasingly rare, increasingly antiquated in the modern cultural landscape, where everything is for sale, at a plummeting cost. In the early 1990s a spot in a Levis ad could net a mill plus - even as recently as 2003 Mogwai got $250,000 for flogging 'Summer' to the jeans brand. Nowadays they'd be lucky to get $20,000. Split that five ways and see how many months rent you're looking at.

But with record sales falling lower than the common denominator, the doors are off the hinges, and "my sweet love" has been ousted as the musician's chief muse, in favour of "my sweet Dove", or whatever. Bands are falling over themselves to provide a suitably whimsical backdrop for the latest phone ad, while brands are ripping through rappers quicker than Violet Elizabeth. Last year Kanye West, Nas, Rakim, and super-conscious political emcee KRS 1 were commissioned to make a song for Nike. More recently Smirnoff paid handsomely for the services of KRS and DJ Premier (an unrepentant KRS noted he made more off that one song than his last four albums combined), while Julian Casablancas hooked up with Pharell and Santagold last month on Converse's buck, to miserable effect.

Some of these songs bear little lyrical relation to the companies that pay for them. Some do. A worrying trend to emerge recently has been that of the four -minute jingle disguised as pop song. Some are as transparent as they are manically risible - earlier this year shampoo brand Fructis invented a Pussycat Dolls styled band called Code Green and hooked them up with perennial laughing stock and Rocafella weed-carrier Memphis Bleek for the brazen 'Fructis Flow', on which Jay'Z's protege raps, "you know just how I do / I can run my fingers through / strong all day it replenish your glow / it turn that dull into soft so girl tell that frizz to get lost".

Others are sneakier. Chris Brown's 'Forever' had been on the charts since May until the song was revealed as a Wrigley's ad ("double your pleasure/double your fun" goes the hook), causing a wave of outrage across ye olde internets - although some were quick to point out the idiocy present in much of the clamour. "He definitely already works for a huge multinational mega-corporation," noted Popwatch. "It's called Sony BMG. Every time you hear a Chris Brown song on the radio, you are hearing a work of popular art which is also an ad: A catchy piece of sound designed to convince you to hand over your money to a rich executive somewhere."

Critics have been quick to point a misguided finger at rap - hip-hop having been on sale since 'My Adidas', after all - but with Groove Armada now officially financed by Bacardi, The Spice Girls' albums selling exclusively through Victoria's Secret, The White Stripes flogging cars and new EMI boss Guy Hands calling for bands to be sponsored "like football teams", don't expect anybody's morals to last for long. We're in a recession, after all.

"Adverts always annoyed me," says former Boo Radley Martin Carr, who until this year ran a strictly no-ads policy with regards to his songs. "I always wanted to create things that were opposite of what an advert was - not that I think they demean the song, I just didn't wanna be in there with everyone else, trying to sell you something... now I've changed my mind, for the same reason. I'm doing it because I need the money. There's been a huge sea change from when I was 20, there was a definite movement that wasn't involved with major labels, wasn't involved with advertising. That was an anathema. Now it's accepted, nobody cares. I still feel regret about it, but I've got more important things to worry about. Having a kid and finding somewhere to live."

Someone's gotta keep your favourite artist in pie and Pampers. And if you downloading swine aren't gonna pay for their services anymore, well, Ronald McDonald might. Even I, moral-high-ground-hogging toolbox that I am, took some Greek bank's buck for a song last year. Shit, Kiddie rap Svengali Jermaine Dupri just launched a record label with TAG. But all the deodorant in the world won't disguise the stench of the music industry's fetid corpse. The horse got flogged into lunch-meat a long time ago.