A person who still looks sexy, even when they haven't kept up with their appearances. It can be used for men and women, and it is derived from the word "Hot Stuff". It describes the beauty in waking up out of bed/etc. and going somewhere without really caring, because you know you're still freaking hot.
Ex. 1
A: "Why are all of these guys going after you?"
Q: "I don't know, man. I mean, I've been pretty scruff all week."
A:"Yeah, you've been wearing sweatpants all week and guys are still like 'Whoa, thats some hot SCRUFF!"
Ex.2
Johnny Depp is some hot scruff in Pirates of the Caribbean.
Sparse facial hair grown by high school students. Students reject the idea that they don't have a real beard and they grow out the sparse facial hairs making them look like an idiot.
Did you see John's sophomorescruff it looks like he glued pubic hair in random places on his face.