I've used Tor before. If buysex.onion was a quality site, I'd consider using it. I'm not aware of an escort site that is only Tor accessible, and I've never looked for one.
I would typically find escorts at the last minute, so I can't speak for what it's like to plan ahead. I'd first search the classifieds for women offering incall (I go to their place, usually a hotel) in San Francisco. Next, I scroll through the ads, only reading ads that have reviews & pictures, looking for the right escort at the right price. When I find an ad the looms promising, I double check the reviews to make sure they aren't horrible, and I also use Google to search for fake images. If everything looks good, I try to contact the escort to book an appointment.
I never wrote reviews on myredbook.
When I visited Australia a few years ago, I visited a legal brothel. All of my of purchases for sexual services were started online. Purchasing sex in Australia was pretty interesting, but I that was the novelty of the legality of the purchase.
I am pretty sure most sex workers were independent, but I have no way of verifying this.
I did not participate in discussions on myredbook.
There were many, many ads on myredbook posed by a person with no reviews, and the pictures in the ad were not the sex worker providing the service. It wouldn't be hard to sell someone on hooking up with a fictional 18 year old, then delivering a 17 year old who clearly isn't the person from the ad. Personally I avoided these ads, but only because I learned through trial and error that meeting sex workers with reviews was usually a better value.
I think my red book safer. I personally behaved myself more because I didn't want to get robbed, or shamed in public.
Regarding the decline of western civilization, people have always been horny, and some people need to pay for lovin' in order to address their horniness. I'm not convinced that paying for sex is related to moral decay. Morality itself is kind of a tricky subject.
I used myredbook to connect with, and buy sexual services from, several dozen of sex workers. I'm also a regular HN reader, and this is a throwaway account created just for this thread. AMA (ask me anything).