I never had the privelege of living by a guy code. It was every man for himself at my high school.
Ever heard of an edit button?
I use the 1-10 scale for how pretty a girl is but if its just a sex thing she is either "fuckable/doable" or shes not. Kinda like a 0-1 scale you mentioned.
When I was at a club with friends and we're talking with some girls, we would just look at each other, and if we got the nod of approval, we'd go for it. You can't trust your own judgement in a dark bar and full of booze. Friends don't let friends go home with 0's.
If you're at a bar trying to.take a girl home, its 1's and 0's. Ain't nobody here turning a 9 down because she is a bitch. If you do, you're looking for a wife in the wrong places. The only thing that matters for a one night stand is looks and that comes down to, would you fuck her or not? A 9 at 2am is probably only a 4 at 7pm. 1-10 system doesn't work.
I know a bunch of my guy friends always use the 0-10 scale when rating how hot a girl is at the bar or wherever