I wonder if Metallica really had an issue with how their music was used, or rather that their music was used. I definitely put them in that category of musicians (Prince, the Beatles, the Smashing Pumpkins) who are overly protective of their music.
The trolls behind #BaldForBieber have launched a campaign to get Bieber fans to cut themselves over his alleged marijuana use (you know, because if there's one thing we know it's that drug use turns artists into complete crap). It's insensitive, to say the least, but there's been some high quality smartass-ery as a result.
Story from Gawker (be warned: contains images of self-harm/cutting)