Having a negative doesn't make it an automatic no to a booking. It really depends on what caused the negative. Some people just don't get on and sometimes it's the punter's fault (hygiene issues, poor comms, poor research during the booking process, expectations incorrectly set, problems following directions to venue, etc.). I generally take all reviews with a pinch of salt and also checkout the reviewer's review history too. Sometimes punters can be wankers and post negatives out of spite. There's always two sides to every story and for the most part you only hear the punter's version on here.
Some punters are fussier and more demanding than others. Some go with the flow and adapt to the SP. It's all part of the experience of seeing different SPs.
The success of a booking is dependent on the behaviour of all the parties involved. It's not all on the SP.
If it's a review related to BB, drug use or poor hygiene then it'll probably be a no.
If the SP has a long list of negatives then most likely a no.
If the SP had a small number of negatives in a long list of positives and the negatives were spread over a decent period of time and the SP had the look I wanted then I'd still book her. I'd be taking a risk, but I'd be going into it with my eyes open.
I look for trends in an SP's feedback. If it's mostly good then I risk it. If it's mostly bad then probably not.