It depends on why the negative was given. If the girl is a thief, blackmailer, psychpath etc I'm definitely not gonna see her. If it sounds like the punter may not have been blameless or the girl was just having an off day, I'd consider seeing her if there were a number of positive reviews to balance it out.
I agree with whoever it was above who said one negative has the same weight as about 4 positive reviews. For me, if a girl has one positive review on here and no other reviews at all, it's still a gamble going to see her