i've had countless bad experiences, mostly because of my eagerness to get bodywork on a given day and lowering my research or communication "standards". one time, i had to ask the guy to stop about 15 minutes in. first and foremost, he seemed pretty out of it, he over-oiled me and applied a bizarre amount of pressure and was trying to get frisky, despite my unwillingness. looking back, i should have been able to see those signs before i even got undressed.
i agree with everyone else in this thread - if your gut says no, it's not going to be good bodywork.
i guess you gotta slay some dragons before you take home a princess?