RE singing on pitch I'm not a natural, to say the least. But some are and don't need to work at it. I'm good at hearing a part and cue'ing someone in but singing's just not my thing, a long time ago I decided the local music scene didn't need one more crappy singer so I leave that to others. It's a treat to be in a band with good harmonies though. One oldies band I play with does a great job on Poco songs.
I fully empathize with being frustrated with a band and struggling to be tactful with suggestions. I have to open my mouth when they butcher chords because "aww that's good enough" or "no one will know the difference". Not a fan of redneck reharms of David Alan Coe songs! lol. It's also hard to keep quiet when someone repeatedly has trouble with the timing of something, when they could fix it just by playing along with the record on their own time, practicing with a click, or just learning how to count. Another bone of contention is when other guys have different ideas of what constitutes a groove. Not in the ranting mood right now but oftentimes I can rant on and on (maybe there needs to be a seperate rant forum?lol) I try to remember I have issues of my own that others are nice enough to work around, being hard-of-hearing.
I also empathize with being conscious of who you're associated with. If it gets to be too much there's always the solo option, as a way to tread water until you can find a band situation you're happy with. What I like about playing solo is, if the music sucks you know it's your own fault and you have total control over making it not suck. But there's nothing like playing with a good band. It's safe to assume that everyone that posts on a Backstage with the Band forum, feels the same way.