Well the site gives the impression of HF level quality. No surprise though as I see most of it is from HF.
Also virus scanners aren't 100% accurate. They are reactive, not proactive. They only guard against well-known and documented 'threats'. However, these are pdf files, I'd like to see any 'crypter' for a pdf. There have been times when arbitrary code has been executed from a pdf but the likelihood is so low on HF that I didn't even bother to analyse the file. Just because the virus scanners don't detect anything, doesn't mean it's safe. And the inverse is also true, just because one does detect it, doesn't mean it's malicious. These programs were never a one-stop solution to anything. They are only to supplement common sense.