I don't generally venture into sites that commonly harbor such nonsense. When I do though, the torrent sites I visit have comments and ratings enabled, so I only download something with at least 4 to 10 seeders minimum (depending on what it is). As for the other kind of sites, I don't generally go on those say for one site that's actually doubles as a fan community (plus its all images). No viruses for me!
Call me a conspiracist, but I believe that the culprits behind malware are (1) people with a cause, e.g. radical Christians uploading malware to adult websites, and (2) people withouth any cause, e.g. a person who knows way too much of what they're doing and doesn't know how to productively spend their time. That's about it :P