UB is my normally stomping grounds and I track about a half dozen regulars there because the 'group' is realatively small. If there are 6 tables going, myself and the other regulars might be taking up as many as 20 of the available seats.

Now compare this to PokerStars. I checked pokersitescout yesterday before playing. It showed 52 active players at 100NL for UB. For PS, it was over 950. Who are you going to pay attention to in that mass? If a refular played there all day, every day ... it's still unlikely you'd play more than 5% of all of you hands with them even sitting at your table. I doubt it's worth any effort to note them.