Fouled Spark Plugs. Can they be cleaned and reused?

Pulled the plugs, they're sooty and black. Can they be cleaned up and reused or should I just go buy new ones? Also, I'm sealing the gas tank, I poured the gas out and it was brown and full or rust and crap. Putting on Uni filters so now I'll have clean air and clean gas. While I had the plugs out I cranked it and had good compression from both cyclinders, I didn't measure it or anything but could feel a good amount of air coming out of both sides. The carbs were rebuilt last summer, but if it was just pumping crap rusty gas through they'll probably need rebuilt again?