if a girl is just gross,  I would probably just walk out. she might threaten me with bs but it's better than me risking blowing chunks during the session or wasting money on someone who isn't as advertised.  

For providers, acting sick would be one of several hassle free ways to weasle out. Most guys don't wanna be the assholes who forces a sick girl to carry through. Claim that you had too much hot sauce earlier in your burrito or something and that you might accidentally squeeze out some brownies during the commotion,  if you don't postpone.  

Maybe even say good bye and claim you'll  "make it up to him" next time. as we all know, that could mean a million things...  lo

Just as a guy who meets a provider who is unclean etc. They have every right to turn around and NOT drop any money and get the hell out.  

I guess what you say depends on a number of factors. Assess the situation, and pick the best route out. Just give him his money back and let it be.

Cut me a break with this! !

Everytime I gotten into the shower with a provider, it's been Nirvana afterward....