When it comes to "YMMV" there is some factors in the control of the client while there is some that is not (on that specific day)
Under client control :
Vibe/Behavior: Obviously how you behave is a big point. If you give a good vibe, its always better. Some peoples have the "entregens" easier than others. In my case it also depend on the vibe of the provider. I am a bit shy still even after all these years but if she make me at ease, i will be a lot more "easy going". I know part of it is on me and a client can also influence positively a provider, so i try my best to overcome my shyness these days. In any case i am always polite and well behave when i arrive because these are "codes" i also apply in my day to day life. For instance it can be things as small as removing your shoes when entering somebody's house. For me it is a normality, but there was peoples i had to remind to do it when they arrived at my place. Therefore when i arrive at an incall obviously i remove my shoes right away. Often behaviors can be to show up sober, to inquire about boundaries, and as funny as it may sound, just act like a normal person.
Hygiene : This is obvious ... no need to expend too much there
Presentation : I am a bit guilty in that departement as i still dress like a person younger than my age. I don't see myself as a "monsieur". I don't buy ties and suits. Its been almost a meme on this board in the past

. But at least i try to appear "presentable". That said considering most escorts are in their 20s or early 30s (i said most, don't crucify me if you are an older provider

) maybe its more relatable to them? I dunno.
NOT under client control
Physical appearance like facial morphology, weight etc. I mean yes ultimately with time and effort you can lose weight but for a booking that happen on a specific date, i am gonna be what i am gonna be. Some providers may simply not attract to older men, or heavier men, and so on. I found out that usually the better providers can work pass that, and appearance is not really important for them, but some have a little more trouble with it and may not want to give more than the "minimum" to someone they are not attracted to.
I mean i had a few rare providers who gave me a cold shower even before i had time to say anything beyond "salut". Either my appearance may have been a turn off for them or the job simply was... In either case i had few control over that. I guess i took a "tofft" because the pictures looked good ...
Anyway i will say that in my 16+ years of doing this, i have been extremely lucky to only have a few "subpar" meetings or if you prefer when attitude, mileage etc was an issue. That said i mostly played safe as well as the few "tofft" i took were still in reputed agencies or indies i knew were friends with other indies that had good reputation.