This too has been my experience, but I don't get out much so I really only know one.
He happened to be the worthless azzmuch that my ex cheated on me with (the FIRST time (that I KNOW of)). He really wasn't that smart either and had the social skills of 3 year old with a poopy diaper.
You're telling me these people get laid? Now they'll never be motivated to become less annoying.