too much testosterone can cause deca dick though. some of the pros who are open about their AAS use have said, on interviews, they could not function in bed due to too much AAS
Moderate AAS use has not been proven to cause impotence. Guards is a big boy, but at 6'4'' you probably don't need too much because you should be close to your natural limit. A moderate amount of test will make you harder than ever but I'm not so optimistic about guys who run 3-5 grams year round.
They do all seem to have tiny dicks especially to be able to fit in those posing tights. I doubt they started bodybuilding due having a small penis though.