So when a provider lists YMMV on her list of services provided - what is she saying really trying to say about herself?

...not the provider. The hobbyist is the one that completes the profile. What that means is that it depends. Each situation is different with each person. She may enjoy kissing with one gentleman, where with another it may not be a favorable experience.  

Because I asked it to be listed as ... "rimming -give and receive-  ymmv" meaning, I'm just highly selective when it comes to that service. Some ladies love to kiss but it may be listed ymmv because even though I/they may love to kiss,  I'm not interested in kissing a fucked up mouth.  
Ymmv is not a bad thing really. I think it's saying the lady is simply selective, atleast that's my experience.  
I am the one that had the ymmv listed on my profile because I definitely don't want EVERY GUY that walks through my door to automatically expect that service. I do enjoy it with the right gentleman but it's rare so it's ymmv.
XOXO  
TL

... whenever I see providers especially South American who have extremely limited English.    I speak fluent Spanish and have found it breaks down all barriers between me and the girls.     I consistently have great time speaking in Spanish with these girls and post a YMMV to fellow hobbyists who cannot communicate in Spanish.

matters!   lol

There are exceptions to every rule!

And, as you have pointed out, it is always good to explore these topics from many different angles . . . . .  

... guys claim to be on the small side or average and then show up with mandingo dicks. It's why I stopped offering Greek on a first date. Second or further dates only. I need to see it for myself on the first dates to approve it for future date.