Absolutely if a girl shows up high you should refuse her - or ask her if she has any to share. But seriously, that would never be a problem and I think consensus is that it is exceedingly rare.
As for writing bad or so so reviews I agree that it is delicate. First of all, I try to separate looks from service. If I don't find a girl hot, that is my taste, but others will always disagree. As long as her appearance matches photos, then I don't say that I find a girls face unattractive. If it was covered in warts and she was missing teeth, that might be a different story. When it comes to service I try to be objective. I try to describe what I like and whether her service matched that. Just because jane from agency X doesn't give head the way I like, doesn't mean she won't do it the way you like.
I also try to keep personality different from looks and service. Your friendliness and engagement are it the same as how well you do cowgirl. Again I try to be objective and describe what happened in the context of what I was doing. If things are less than perfect, I do look for reasons why she might be a good fit for others. Maybe this girl didn't like kissing me because of my facial hair; maybe things didn't click with that girl because she was waiting for me to direct her and I wasn't doing that. I try to give the benefit of the doubt while also giving readers accurate information to help them find the best matches because the reviews on this board have been so helpful to me.
I never see any reason to be mean or personal. I have written one review the was totally negative because the session was horrible, but I still tried to keep it professional. Since I visit from out of town, I write all my reviews immediately after the session, but I do not post until I return to boston. I re read everything and make edits before posting all reviews at once. It helps to make adjustents after a day or 2