The whole golden rule thingy is kind of the only thing to go by. "Do unto others...". Michael Shermer talks about that shit at length in his books and why it makes good biological sense as well. Sonny Barger had a quote that I've tried to live by: " Treat me good, and I'll treat you better. Treat me bad, and I'll treat you worse.".
_________________________
"I'll never forget the moment during the lovely Alyssa Allure's scene in 'American Bukkake' where the fellow got out of his wheel chair to ejaculate on her face. It was grotesque but had a certain frisson." -Sock