The first thing I did was remove DefaultTrust after the trust system was created. I put in only people that I've had actual dealings with or scammers that I personally identified as such. I think the only way to actually see if you are in Default Trust is to add it, which is partly to blame for my confusion. From this post, I was able to determine that there are no notifications when people add you into their Trust lists, so I really did get no warning.

I guess I don't mind, I just don't remember explicitly agreeing to be in there or doing any specific trades with the folks that are in there so the recent PMs asking me to look into scammers kind of caught me off-guard.