Hello Marty! First off, as usual, you are a killer guitar player! Here's something that has been on my mind for quite some time;

Have you ever walked out of a gig (maybe in teen years or anytime) because you couldn't stand the horrible sound?

Here in Singapore organizers give only 5 minutes to set up and no sound check and I very much dislike the idea of not having done research for this matter. Turns out, the overall sound balance and what not, is horrible!

It's happened to me so many times, what should I do?

Good one!
No! If you wanna be a pro, you gotta prepare beforehand to have good sound. And if you get to the venue and it still sucks, you still have to go on with the show and make the best of it!