That's a separate discussion, and could easily devolve into some approximation of "Is Batman Lawful Good?"
The point is, I think someone could make a character very much like Leon and take a low CHA and Uncouth. (Also, on the subject, really what's it matter what the CHA score is with Uncouth, since you can't default on those tests you don't have the skills for? A CHA 8 elf shaman who takes Uncouth is just as bad socially as a CHA 1 sam, except on the skills he actually pays double for, which probably won't be that many because he'll spend more points buying a few skills at 1 than he's getting for the 20pt flaw.)
If I had to pick and Uncouth character, I guess I'd pick Sheldon from Big Bang Theory. He's not the dictionary definition of "uncouth" (in fact, he's reasonably well-mannered), but he pretty much misunderstands all social conventions. Basically every episode is him either him glitching or crit glitching a social test so that hilarity can ensue.
Edit: Aha, I see that UmaroVI said much the same thing, but more succinctly.