I'm in a couple of jazz combos and large group at my college, and we always have problems with one of our guitarists.
We have two, instead of having a piano..
anyway, every day at practice, the instructor has to tell this one guitarist to stop playing between songs. Of course hes turned all the way up. The worst part is hes playing a hollowbody epiphone, so even witht he volume down you can sort of hear yourself quietly to practice a lick or something.
Also, in jazz charts he drops the form, plays 12 bars instead of 16, or 32.... It gets very frustrating for me since i have put in the effort to get the charts memorized, and he can't even read the music and follow it. Luckily the drummer and I are used to it, so we can usually cover it up and end together.
We have the same problem with our mandolin player. He is very good musically, but as far as playing when he shouldn't, or being too loud...its just crazy. I honestly walked out on tuesday because i've had enough of this stuff.
Oh, and changing things last minute right before a gig. I mean, most people can handle this, but when you don't have a grasp on the song in the first place, changing things and then forgetting them in the song just doesn't cut it.
Meh, at least i'm transferring.