Speaking of the bass to loud thing, I have witnessed this and it sucks every time. For some reason the FOH guy wants a metal band to sound like rap or some shit and burys the guitar in the FOH and makes the bass and kick retarded loud. Fuck that shit.
True stories:
Went to the NYS fair in Syracuse. There were bands there playing at multiple stages, anyhow the indie rock stuff I was watching was good. In other words, the talent was there. The FOH guys were just retards for multiple reasons: They refused to use compression (according to the sponser of the stage, a local studio in my area) on anything so it literally sounded like their drivers where smacking into the grills on the speakers they had (not the actual case, I just want you to understand how fucking awful it was). The moron behind the desk panned the guitar on the right all the way right, the bass player (standing on the left) all the way left and it sounded like the drums were panned in a similar fashion. Result? Well obviously we can't hear the fucking guitarist very well and the stereo image was horrid (even standing dead center stage both back to front and side to side.
Another time we had this old prick who knew fuck all it seemed because he did the FOH mix, and let it a lone. Yeah that's fine except the kick was obviously cliping either the speakers or the board because it sounded like muddy fwoppy shit. You know the sound, like when your mixing and you take the fader on your kick and you crank it up till it clips, only this was MUCH MUCH WORSE. So my drummer, being somewhat of a cocky fuck, goes and turns it down a tad. Bingo, the clarity comes and the kick sounds fine. Fast forward a couple songs and we go on. Douchebag old guy who obviously can't hear a fucking thing turns it back up.
I have had good sound men as well so don't take this as a general "all soundmen are morons" example. It just seems like there is an endless amount of hacks out there trying to do sound and failing miserably at it.