I've made the mistake before of playing originals in an ordinary boozer... On one memorable gig our metal guitarist was just starting his extended solo as a hen and a stag party walked in. He was widdling away happily, eyes closed,fingers tapping merrily when a drunken girl staggered over to him wearing a skirt I'd barely class as a belt - she shouted "can you play "'Summer of 69'?". To his credit he stopped his solo there and then, shouted the key (I'd never played the song) and we did a quick chorus, then straight back into widdly metal. Punters barely noticed as they were so busy sniffing round one another!
So now we only play dedicated music venues and festivals, cos folks there come specifically for the music...