@NEcroraven
I don't see this really in "older" metal fans. I'm proud to say I have a Slayer tattoo. I was never really worried about deciding one day that "hey, slayer sucks now", and regretting ever getting the tattoo. Granted I've been jamming out to Slayer for 10 years now. I would say it's a terrible idea if you have only recently discovered them(say, you haven't been listening to them for 5+ years), because the example you posted is extremely likely.
I've been thinking about getting a CoB tattoo for a while now, but I want two things from it. One being that you can tell it's a CoB tattoo, and two being that you can tell by something other than having their name/acronym spelled out. I'm saying another fan could tell pretty easily, and would immediately recognize it if I pointed it out, not that some Fallout Boy fan could tell if they saw it. God Forbid that day come, I may have to sever the limb off.