I turned down a few things like this a few years back, but it appears to be becoming increasingly normalized (especially as banner ad revenues have dropped and dropped with cheap Google Ads and Facebook promotions bringing the price lower and lower). I haven't seen many music sites doing this sort of thing, and I obviously err on the side of caution of entering into anything that doesn't feel right, but perhaps I've been being 'too indie' about wanting to keep editorial and advertising completely separate.
Would you be ok with it? Obviously sponsored stuff would be clearly marked as such, and obviously wouldn't be things like sponsored reviews. Most of the things we've been considering doing recently have been giveaways and stuff like posting video content from brands or trailers for movies.
I ask because this article has made me rethink the concept a bit: http://www.digiday.com/publishers/does-sponsored-content-have-a-labeling-problem/