GUEST - you mentioned a "paying audience". If that means you're charging admission at the door, you have a responsibility to keep the level of talent relative to the door charge, and keep the really bad ones out. People don't like to pay to get into bars/nightclubs in the first place, and if you don't make them feel that they're getting their money's worth, they will quit coming in.

If you only meant "audience paying for beer", you can afford to be more tolerant of beginners. I began my public performance "career" (more a "careen", as Richard Thompson used to say) playing open mics, and that was extremely useful to me for overcoming stage fright and developing an idea of how to address an audience. I've been playing semi-professionally for 16 years now.

As far as telling someone he/she sucks, I'm all for it (if it's done with kindness), but these days many shrink from leveling any criticism at all, however well deserved, for fear of appearing impolite or hurting someone's feelings.

Cheers,
Michael