Guitarists turn up periodically because of something called "Temporary Threshold Shift". After a little time at a certain volume, the ears become accustomed to the abuse, requiring more volume to get the same perceived effect. Most musicians are unaware that this happens; just watch your average bar band. After three or four tunes, just like clockwork, the guitar players will turn up; after a few more, turn up again. The best thing you can do is protect your ears even if no one else has the sense to do the same.