Another justification for the "don't piss off the sound man" maxim is: he is the guy who has control of the fader on the bass channel, and the power to use it. Case in point, at an Elvis Costello & the Attractions show that I attended in the early '80's, the bass was completely inaudible through the entire set. I could only guess, knowing a bit about Bruce Thomas' temperament, that he did something to alienate the FOH engineer which caused him to retaliate by taking Bruce completely out of the mix. I could be wrong, but if it was a technical problem they would have attempted to fix it while the show was going on.
Anyway, the lesson for me was, no matter how much of an idiot your FOH mixer is, being antagonistic towards them won't help. I've been in situations on tours where the band is unhappy with FOH or monitor engineers, and if the complaints are legitimate they will eventually be addressed one way or another. I was on a tour where we went through three monitor mixers in 7 weeks, and that wasn't because of any diva behavior on the part of the band - the mixers were actually incompetent or psycho (both in one case) except for the guy who finished out the run. Because the production manager cared enough about making the band happy, he was willing to make changes until they got it right. Even in a club situation, where the pay scale may be less, the sound man could be the owner's brother or the owner couldn't give two ***** about the sound, enough squawking will get results eventually.