Texas Guest, I can go along with the "whore" description but at least a whore (usually) gets paid. Seems to me that most of my "gigs from hell" have been freebies for good causes. I've lost count of the number of times I've been told I can sing while folks are attacking the food tables, while groups have been setting up on the stage behind me (including doing sound checks) or when the chairs were being cleared away for the dancing to follow.
Just about the worst was a fund-raising event for a local children's charity which turned out to be an indoor fleamarket. I was installed in a corner with no amplification and expected to sing for the full four hours of operation. The event was very poorly attended by the public so the first hour was actually not too bad. I finally drew the line at being presented with a hurriedly and very badly prepared banner which I was supposed to wear on my back while wandering through the local shopping mall! Had permission been sought from the management? "Well, no but they'll understand!"
Why did I feel so guilty at declining?
I'm inclined towards the philosophy that people don't appreciate what they get for free but to be honest, I've had some great gigs from which I came away feeling very enriched in other ways.
Then there was the St Patrick's Day gig in a strip bar in Jacksonville, Florida but that's another, and rather personal, story!

Eddie