I'm taking just a tiny step to the side here and note that my most common note - not because it's the most common feature in players but because it's something I always note when I see it - is "compulsive slowplayer."
You know the kind. Bets every flop except when he hits a set at which point he cleverly checks back. Or is willing to go all-in with a flushdraw, but won't raise the actual flush. Of all the notes I write, this one I value more than anything else because it basically tells
me that when he bets it, he doesn't have a monster. And that's pretty darn valuable information.
Now, just slowplaying a set doesn't qualify. On a dry board vs a single opponent with a wide range, there's nothing particularly wrong with slowplaying a set. But checking the flop when you hit trips and then min-checkraise the K-high turn in a tiny pot is typical behavior of a player who just can't stand the idea of losing his customer.
So, "comp slowplayer" is my most favoritest note.