then again there's a lot going on in those first few seconds, so sometimes it's a bit hard to separate the events.

I can think of a few that the initial reception was a bit on the cool side, but as the evening wore on, things got a lot more heated.

I can think of one that started pretty good, but then found myself not enjoying the session as much as I had hoped for various reasons.

On rare occasions they will, but for the most part, I realize that sometimes people are just nervous, and that can change a person's personality/approach immensely. Someone who may come across as distant or not really "there", may just be nervous...which usually subsides within the first 20 minutes or so...although some are still nervous up until the end, but on subsequent appointments are more themselves.  

I have found that in many situations, the first impression an individual portrays (those first 5-10 minutes), will let me know if we are compatible or not...sometimes people just do not "click", for whatever reason..no matter how hard you try, there's just something there that rubs the other person the wrong way...thankfully, these situations are few and far between

I focus on doing my part in creating good chemistry from the outset.....

I make up my mind to "like" her as long as she is as advertised and makes any effort
and I take responsibility for making the latter easier for her....

I almost always experience good chemistry and it does hold up -   I rarely repeat with providers though so cannot speak to that issue....

I have experienced a negative or lack of connection or whatever occasionally and I believe that this is just personalities that do not click.....  almost (but not always) able to enjoy good sex anyway as the ladies are quite professional (and so am I at this point I guess lol)  but the sessions are a lot less memorable.....