Oh, and another factor, which is a problem, are illegitimate reviews. Either written by the spa/agency itself, or farmed out to professional shills who are paid to write glowing reviews, and even legit reviews where someone might receive a discount for a review (sometimes implied a favorable one, though not always).
If you hobby long enough or frequently enough, I'm sure many guys have received some type of latter offer. Some guys are swayed by the discount and will write a review that tends to be more favorable (or at least less critical), while other guys write what they really think, regardless of the discount. "Reviewer's special" is relatively common, and certain agencies (and indies) openly advertise it.
Also, some guys will only write favorable reviews and not write negative reviews, for a number of reasons. They don't want to destroy a provider's reputation/harm her business, or they really like the shop otherwise and don't want to badmouth any of their providers, or just generally don't like to say negative things at all.
The bottom line is...make sure you do your homework. Review the reviewer...can't stress that enough. Certain things to look out for include:
Every review they post is positive (all mid 20s, beautiful, with amazing service), and not a single negative one.
Only reviews 1 shop or the same 3-4 shops repeatedly. Goes hand in hand with the first statement above.
Adamantly defends or "white knights" a particular provider or shop, in multiple threads. Conversely, always trashes a particular provider or shop and is borderline stalk-ish.
The board's policy is that we are not here to police anyone, nor is it responsible for accuracy. It is up to each member to do their own due diligence, police themselves, and come to their own conclusion.
From TJ himself: "...it is no place for a mod to decide what review is real and what review is fake. Mods shouldn’t go pulling reviews or deeming members shills or taking stances against certain establishment. Mods are NOT police. Members police each other."
Once again, do your homework.