I'm in agreement over looks. For performance, I'd think that going below a threshold like 4 would require something extraordinary that isn't made up for in the session. For example, I recently had a kinda ridiculous experience with a provider not being able to get a hotel room for a few reasons and it took more than an hour of waiting until I got in the room, but I had an awesome time there after that was over. When I say awesome time, I haven't had that much fun in any other context in recent memory. If I got into the room and I were being pushed out within 20 minutes because that counted towards my time, or she just wasn't interested in being there and had an attitude, that'd be completely different and warrant a 1 or 2.

Bad hygiene, Upsell, Rushing you ou the door,

Positions herself to hide the bj and giving you a covered hand job while bobbing her head up and down to sell it as a bj.  

Squeezing her legs against you while in Mish to keep you from going any deeper than an inch.  

Providing during her monthly so FS is out,  but charging the same.

Let's you know through her attitude and actions that she's too good to be fucking the likes of you and would rather be having an un-novacained root canal.  

Shutting it down after 10 minutes and saying you're taking to long.  

Being stoned or high during the session to the point that it just isn't worth staying even though she'll funk you.  

Need I go on.   And yes,  it's all happened to me at some point in my hobbling,  and yes,  the all had good reviews on their profiles.

In my mind, a 5 or 6 is just dull, uninspired sex, whereas a 2 denotes something truly awful, like hostility, dishonesty, uncleanliness, etc.  A 5 or 6 is "I won't see her again, but YMMV", and a 2 is "I wouldn't fuck her again with your dick."

I know many providers who don't even rate a 7 overall, but they are good providers with pages of reviews. If you mean the 10/10 provider who occasionally gets a 2, well...I've not seen that happen too often. She might get the occasional 7, but lower than a 5 is a bit odd unless she has A LOT of white knights lying for her or had a seriously off day.