I try to find out what people want from a band when I first get involved - If they all want different things, they'll need to compromise, and if they can't, I'll walk away...I still give things a chance, but I think it's important to look after what you want yourself. I think it's good to keep your options open, play in a couple of bands, or if that's too much, have one main commitment and occasional jams with other musicians, then if anything goes wrong, you haven't lost everything - you can keep playing and keep motivated.
I suppose it's quite easy for me to say that, as I'm in several bands, but out of those, only one is ever really busy at any one time. They all know my situation, and they accept it. If they didn't, I'd have to accept that I couldn't play in that particular band, but I've got other options that I can focus on.
I hate the politics thing, and I've spent a few years developing a way to deal with it that works for me...I think it will always be a problem, even in a good band, I think it's how you deal with it that really makes the difference.
Hope this helps.