I'm a dude, and average really (think, uh, Jim Carrey?). Had a couple of relationships and my share of wild nights in college. I liked all those girls a lot but some of them were very popular and I've had to fend off several "hot dudes", some of whom I've seen on TV since. So, I've probably been someone else's "ugly ***".
Dating is a numbers game: as long as he's got basic stuff in order (i.e.
hygiene, I wonder what some people do in the morning), an average dude with lots of friends in a psychology faculty will have better odds than a hot dude whose social life amounts to one DnD night per week at Mark's place.
Regarding looks, I think that, once you are attractive enough that the girl says "ok I'd go to bed with this guy" then returns diminish. Going from "obese" to "okay" will improve your success tremendously cuz obesity is universally unattractive, but going from "okay" to "very fit" will not do as much, as you were probably already a "yes" for most girls you'll interact with. In reality, most of the "ugly ***" guys that are with attractive girls are actually okay-ish, they may even be tall, masculine or stylish when you look at them closer. A good example would be Adriana Lima dating Marko Jaric. Ok, she's an atomic bomb and he's got a funny face but the guy's damn tall, masculine and a successful pro athlete to boot, he'd be a "yes" in most women's books:
That's the big trend re looks IMO. Then, you've got other stuff going on like her personal preferences (based on real life examples: she only dates Arabs, she likes blond guys, she has a crush on a singer who vaguely looks like you, she loves Italian culture, she's big into heavy metal, etc.), money, status, etc.