You Americans must have crappy karate schools. Here in New Zeland, in my club, the black belts are all very accomplished. I wouldn't mind a friendly spar with you, just to show you that karate is a useful martial art, when you can trace it's lineage. I hate it when I see things like "Red Dragon Karate" etc (Mc Dojos), the traditional unmodernised arts are the best. Modernising has done little but water down karate, if you study traditional Okinawan karate, e.g. Goju Ryu, Shotokan, you find a strong art that's even too dangerous and brutal for full contact sparring.
I used to think Kung Fu and Taekwondo were weak and useless, till I saw proficient practitioners from strong linage schools and my opinion was instantly changed.