I believe it's based on number of posts and replies you make. Cuz I've seen plenty of people who have hundreds of posts but it's always the same desperate dribble wanting easy play. They're listed as members and not newbie. So clearly it's not a quality based thing lol.
Basically that's correct, I believe the thresholds are 30 (kinktalk member) and 100 (senior member) posts. Status can also be changed for females by verifying and mods and admins at will.