When it comes to sweet, I think 50% rests on the gentleman being a gentleman. Having said that, I have only met a few that would not make the list, but then, I never revisit them. :-) My list would be (in alphabetical order only):
Angel Pie (she's quiet, but she is very sweet. She's due a review, coming soon)
Crystal Kitty (just a darling)
Kat (Kit Kat - long time favorite)
Sarah Smiles (I'm just getting to know Sarah and find her very sweet)
Sweet Sonia (I had a double with Sonia and Kat a couple of years ago - WOW!)