In my limited experience, when a session is a group of individuals it seems to run more democratically, but when it's dominated by a group, a band, with their own agenda, it's hard to get a note in. Walk away.

As for loud instruments, the ever present guitar has a hard time soloing with banjos, pipes, whistles, and others who won't give way. Sometimes it doesn't matter what instrument one plays, there are just too many players at a time, and too few with the good grace to sit one or two out. Walk away.

Peace, Mooh.