I'll bet a lot of spammers and abusers and also use Tor, and Tor exit points are limited. If I happen to be assigned a Tor endpoint that was recently used to abuse the StackExchange or Reddit, they could falsely believe I'm the one responsible. Is it safe or a good idea to use these sites over Tor?
Ther is a SSL/TLS fingerprint who avoid tahat you get someone alse ID. Ther are more identifications which separates users. Do not believe that your anonymes because your using Tor.