I recently came across an old article in Pitchfork, in which the band The Thermals talked about turning down a massive amount of money to have their song "It's Trivia" used in a Hummer Commercial. While calling someone a "sellout" is one of those great, meaningless rock cliches, it was nice to get a refresher on just why certain bands avoid the risks and accusations that come with doing so.
There are certain bands for whom credibility is essential. Although they will never make a fortune, their fans will stick with them for years because their music is honest and personal and not created for the sole purpose of fame and fortune. Bands like Fugazi, The Thermals and many others have built a reputation upon being the kind of band that wants to make music first and money second. Once you've developed a fan base, the only way to lose these fans is to make a big stab for commercial success and money. Consider the case of Moby:
Its been 10 years since Moby's album "Play" came out. It was a revolutionary record, both in terms of his melding of blues and electronic music and his jaw-dropping willingness to sell, then re-sell every single track on the record to the highest bidder. What followed was an amazing transition, as he went from a much-loved underground electronic artist known for making challenging and creative records to a boa-wearing MTV star within a year. Moby's music became so ubiquitous that for a while every time a tv show went to commercial the odds were strong that you would hear a snippet of one or two songs from Play. It quickly became a annoying, and eventually sickening, thing to witness.
Within a year, music fans were turning away from Moby in droves. His eco-friendly message reeked of painful hypocrisy, especially as there wasn't a major car company that hadn't bought a song or two from "Play" during Moby's licensing frenzy. While he had successful roped in the Soccer Moms and Starbucks cd buyers, he had lost the die-hards that had allowed him to get into the record stores to begin with.
Ten years later: Moby is considered, at best, irrelevant, by most serious music fans. The Soccer Moms have moved on to the Michael Buble's of the world. He spins records at half-empty ballrooms in Brooklyn. His artistic credibility is so wrecked it may as well have never existed.
If making music is not your primary reason for being a musician, I don't think you that can ever really "sell out." There's nothing wrong with being in music primarily for the fame, or the drugs, or the sex, or whatever, but you also can't pretend to have any credibility if that is the case, either. Moby was a particularly egregious case because he wouldn't stop pretending he was the same old guy long after he'd made his successful bid for stardom. Most bands, however, don't try to pull off that sort of insincere nonsense, and that's why most of the time it doesn't really bother me when I hear some semi-famous band on tv, even if I really like the song.
No credibility to lose=no problem.