Actually if there's one thing worse than music being used in adverts, is when the artist has obviously refused to give permission to use their music, but the advertisers then go ahead and use essentially the same song, but slightly alter the music.
I remember not too long ago an advert for some new digital channel, which just blatently used Rebellion (Lies) by Arcade Fire, except all they done is slightly change the key at the end.
I imagine this goes on all the time; a friend of mine used to do rather well for himself in this line.
Cable channels would come to him with their favourite song by The Prodigy (-or whoever) and just ask him to knock up a version as close to it as possible (-but different enough that they'd avoid copyright infringement and major royalties, etc).
