I guess I've always looked at boards like perb, and the Internet in general, as giant coffee shops. There's lots of advice and stories floating around, and you have to filter the truth from the BS.
If you don't know any of these guys from anywhere, you kinda have to listen to them for awhile (posting history) and go by if what they have said in the past is consistent (including personal biases, which tend to show up if someone talks for long enough) and useful/entertaining info shared (eg: "he's a hell of a storyteller, but I don't think the thing with the one-legged girl and the monkey really happened!")
Most people are concerned to some extent about their health and that of those they have intimate relationships with; there is probably more agreement at the extremes (eg: don't have unprotected sex with someone who has frequent unprotected sex with strangers AND has visible signs of STD/Intravenous Drug use and so on cf having safe sex with someone who has a rep for safe sex and being somewhat selective about who they sleep with), and more grey areas in between (bbbj, protected sex with someone who MAY have unprotected sex with others etc)
A "no-fly" list is a heads-up. Depending on the individual (personal biases, bad personal interactions, hangups etc) the list in question may not accurately reflect what YOU personally are OK with. But if someone is on ANYONE's no-fly list, you kinda have to evaluate what you know of the SP in question, and what you know of the 'gatekeeper', and decide where she belongs on YOUR list, or potential list.
