I don't think overhype is a thing, it's just how well or poorly the review is written and interpreted.
Using Gia as an example, since OP mentioned her:
She is great for newbie mongers, as she sets the standard for a KAMP experience, having a good attitude, high energy, nice body, and older than you were expecting/hoping, lol. Most importantly, she is consistent. I would give her 7/9/8/8, as she is older, but still beautiful, has six pack lines, and is a nice pro. Many others, who focus on youthful looks would give much different scores.
If you've been mongering for a while and she's not your type, it'd probably a mediocre experience, bordering on negative, given the premium price point.
When reading reviews, look at the person's history or any other way to contextualize their taste. Half the hype and claims of shilling are from newbies rationalizing a meh experience or just straight up not ever had good sex in their civvie life.
And as always YMMV, maybe you got bad luck and she caught a cold that day, or ate something bad, or any number of reasons. You may have saved up all month for an appointment, but for her, it's another day at work.