I just did a gig where the soundman could not leave the PA alone once he got me up and running. The PA kep squeeking and ringing throughout my performance (and the following band) He came up to me expecting praise at the end of the show and I was Honest (but polite) when I said, "It was a bit bright and that distracted me from my performance and the performance of the band following me that I wanted to watch" (translation: Stop Fucking with the Gawdamn PA and unless there is a problem quite bugging folks on stage while they are playing!) I soldiered through my solo set, but I never quite got into my stride. It wasn't the worst set I have done and the guy was nice enough so I didn't say what I was thinking to him. I hoped my honest coments of "if it ain't broke don't fix it in the mix" meant something to him. Probably not, but at least I tried to be constructive.
the next night thing were better with my band. I am so used to balancing my band's stage volume I almost never need to put them through the PA. I just had vocals that night. It went well and my ears aren't ringing too hard today (LOL). I hope this helps you all out in your quest for good stage sound.