Well, as a gig whore none of this is a problem any more. But when I was actually part of the rat-race of "being in bands"...
1) Money.
Either outright lies, or trying to juggle figures so more ends up in their pocket. Worst offenders in my experience for this are where there's a married-or-might-as-well-be couple "running" the band. Don't get me started...
Now as a gig whore on a pre agreed pay, if I get screwed it's outright theft and I take appropriate action.
2) Band changes direction frequently.
Worst example was a Western Swing band I joined. Had a couple of hot multi-instrumentalists in it. Unfortunately after about a month one quit and then the other decided he was running things, which was sorta okay, except it got to the stage where one week we were gonna become a Cabaret band, then a week later we were gonna be an Electric 50's/ Rockabilly band, then a Country band, then a ..., well you get the idea. Worst thing was we could cover all these genres appropriately, but the band never settled on one identity.
3) Substance over-use/dependence.
Anything - booze, grass, speed, smack; sorry guys, IT DOES NOT MAKE YOU A CREATIVE/GOOD MUSICIAN. IT TURNS YOU INTO AN EMBARRASSMENT AND MAKES YOU TYPE EVERYTHING IN CAPS.
4) Endless rehearsing with no actual plan in place.
i.e. A strategy for getting gigs, or where we wanna be in one month, six months, one year etc. Anyone who's been around the block will have been in a few of these.
As a gig whore rehearsals are paid and if they wanna waste time...
5) Being idiots at a gig.
Unfortunately if JUST ONE member of the band, or someone associated with the band, acts like a frickinidjit, the bar owner/general public perceives the WHOLE BAND as a bunch of frickinidjits. It might not be fair, or true, but it's a fact of life. So the next time the Singer's boyfriend decides it'll be real cool to do a burnout in the car park on his Hog, don't wonder why you don't get asked back. True story.