Ryan is right about 'not having to know how to act',....... if the "actor' fits the part and the director knows how to direct him/her. It also involves a great editor.
I've been on set a few times with horrendous actors, but a good director can make a bad actor look good on screen but it takes a bit longer and rolling stock is not cheap.
One director is notorious for rolling film during pre-scene rehersals thereby filming a bad actor while he doesn't expect it. And you'd be amazed how good an editor can make one look if he has adequate footage.
I have been told numerous times that the art of making film is no longer in the hands of the artist; but is now in the hands of the bean counters.... and those bean counters don't think a film can be profitable using an unknown "actor" even if he fits the part perfectly.
I personally think that Superman and the other super-heros should look like the figures as the artists originally intended and not animated, computer generated characters nor skinny, non-muscular actors.
No intent to embarrass you here, Ryan, but when you were in contest condition; you could have been the ideal Superboy character and with the right script, a good director, and a great editor you'd be flying around Hollywood in no time.