As previously stated, Join Date is a pretty moot point compared to Post Count. For instance, some one might only post once a month and have been here 2 years, as opposed to some one who joined 5 months ago and posts 5 times a day.
Anyways, I do my research now. I check when the person registered and how many posts they have made. I typically don't try to start up anything with a person under 100 - 200 posts. From there, I go to check their On/Offs. If they don't have them, I will generally avoid. If they pass those first two checks, then I look at their profile (avatars are always a bonus) and their last posts. If their last posts are 90% in the Fun/Games area, then I typically avoid them all together. If its mostly games, then i check out their posts and see their style etc.
Vek also mentioned a new profile change in the works a long time ago? Whats the latest on that?