Be very suspect about reviews if hobbyist has many reviews but NO whitelist.

Providers are real people with real lives.  In a way provider is a surrogate.  Treat her as such and you'll be rewarded...treat her like a piece of meat and you'll get what you deserve!

I'm just wondering if there's an etiquette issue concerning asking about a negative review.  There's a provider I'm scoping out that has mostly 9's but, recently got hit with a stinker.

there is a sufficient number of good-great reviews.  Sometimes a guy and a lady just do not click.  It could also have been an issue with him such as poor hygiene, smoker's breath, etc..

Reviews are a lot like Olympic diving scores. Throw out the best, throw out the worst, and see how the rest average out. Any provider might have an off night. Any reviewer might write things that, on sober second thought, he might want to (but never actually bother to) take back. Or his negative review might be based on factors (tattoos not visible in her pictures, pierced nipples and/or clit) that aren't important for you. In any case, read carefully what the reviewer has to say and decide for yourself whether he is credible.

As to your question, a polite inquiry diplomatically phrased may get you the information you're looking for. Or it may not. Either way, I don't think it's worth the effort.

Check the reviewer who gave her the bad review,  some reviewers just give low scores to everyone they see no matter how good the lady is.  Also if this reviewer is new,  sometimes newbies  don't grasp the review numbers and score either to low or to high. Bottom line, I would NOT let one negative review stop me from seeing a provider

Throw out the  2 highest and the 2lowest. More than likely that is where you will end up.

I suppose I should have added the lack of a whitelist should be tempered with tone of the reviews.  A wise provider will take a reviewer's attitude into consideration beforehand.  There are hobbyists out there who get their kicks "taking down" a highly reviewed provider and that does everyone a disservice.

One of ATF's has mostly 7's & 8"s in all of her total 25 reviews which goes back to the middle of last year.  She has a few 2's and 3's, but when I read the low reviews, I found that the reviewer wanted the provider to do something that wasn't on her menu, or the chemistry wasn't there.

However I would give her a try, and she what she's about if I were you

That would cause you to be suspect of little ole me.  I've turned off the display of my whitelist, mainly because I think ladies could try to use it as a tool.  I think the mod is cool, implying that I've seen her and giving her credibility.  All of mine are legit, but it was a preemptive strike.