When you strip away all the other aspects, what this is is essentially a business arrangement: you are agreeing to accept X in return for providing certain services for Y amount of time. If you advertise as providing services A, B, and C for amount X, then the customer rightly expects to be provided with A, B, and C for Y amount of time. If the customer does not receive any or all of A, B, or C and/or you cut short the session before Y amount of time passes for reasons beyond his control (i.e. your refusal for reasons other than physical), the customer will rightly be disappointed, and will reflect that disappointment in his review.
That's Business 101. Simple. Every business on the planet operates in that fashion.
Now, negotiating the price always seemed like a boorish thing to do, but the reality is that some customers will attempt to do it, and some providers allow it (and some even explicitly state on their ads/websites that they give discounts for various reasons, such as being a repeat customer within X days). If you and the customer negotiate and agree on a price below X, that does not entitle you to withhold advertised services *unless explicitly stated during the negotiation*, because doing so is acting in bad faith. Example: you agree to knock $50 off the amount, but in return, you state that you will not provide service A. If the customer agrees to this, then yes, I agree that he has no right to complain that service A was not provided. If, on the other hand, you do not state that service A will not be provided, the customer will still have that expectation, and if he does not get it, he has every right to mention it in his review because you will not have honored your end of the contract.
Now, I'm well aware that there are bad eggs on both sides of the equation. However, your rant painted with a pretty wide brush, which I don't think is fair at all. And again, this is purely a business thing; it isn't an "evil, dastardly, anti-TS" thing, because these same rules apply across the board (TS, genetic female and male, massage-only, etc.). Bottom line: if you're really that jaded, then perhaps this is a sign you're getting burned out on the business and need to take a break, but please don't start painting all clients with that wide brush, because I do believe that most of us are decent guys who will give a girl a fair shot as long as the girl is equally fair with him. That's what keeps this hobby going, after all.