You really have to consider what type of a client you are as well, know if you are the type that is looking for a transaction or a personal service. That may sound odd but that is where the "YMMV" factor comes in. If you think of a date as a physical transaction, something where you just want to get in and get out, a 'wham-bam' where it's just a series of acronyms then the YMMV factor isn't going to be nearly as much of an issue as you think. If on the other hand you are looking for more of a personal connection, something that has that certain je ne sais quoi then YMMV will be a major determining factor in your date.
As an example, if you have an idea that you would like to see a lady for 30min, you are concerned that on her 'menu' she lists CBJ/BBBJ but her reviews all state that she has given clients BBBJ. Let's assume your biggest concern is that you don't want to get there and be the guy that gets the CBJ. You are not interested in talking to her beyond the standard hellos, it's 30min, you don't really have a lot of chit-chat time. It's about a sexual service, nothing more and nothing less for you. You go in, say hello and ask her about her day, wash up and make a point of showing her you wash up and are polite, clean and pay up front to be sure she knows she doesn't have to worry about any debates with you in regards to being paid. You very likely are going to be like the other guys that have reviewed her and are going to receive what you define as YMMV, you will (likely) receive a BBBJ. It is often as simple as being clean, polite and respectful.
Now lets assume that you are the type of client that likes something that is more personal and values the connection over a list of acronyms. That type of YMMV is much harder to determine but at the same time it's something that when a potential date finds it they tend to revel in it. It's not about the acronyms involved but rather about the friendship, companionship or sexual chemistry, basically what's going on in the brain to make them feel good. The YMMV in that case isn't that you may or may not receive the same sexual services but rather that you may not have the same chemistry, what goes on between the individuals may or may not be sexual acrobatics but like all good sex it's what happens in the mind that made it exceptional.
It's not as easy to determine this type of chemistry in advance, the ladies try to screen for it, I can often tell in an email if a client is not suited for me based on his communication but sometimes I am unable to tell if there will be chemistry or not as there are always factors that are out of my control. There are always people that I have met where I wish I could have a "do-over", where I know given different circumstances things may have worked out better but for a particular reason the chemistry just wasn't what it should have (or could have) been. That isn't something I can control.
YMMV means different things to different people and it always comes down to not only how you behave but what your definitions and expectations are. In the end find the people that you relate to on the board and know not only what type of client you are but the type of companion that best suits the service you are seeking, it's not a one size fits all type of industry, there are different ladies that cater to all types of clients.