The threads I'm referring to would be in the engine, not on the plugs themselves.

Can I use a carb cleaner?

The problem is I need to change the spark plugs, all four were fouled and had oil on the threads. The fouling was caused by improper timing, however the oil on the threads may have been caused by improper tightening of the plugs when they were installed. Now I need to clean the threads before I put the new plugs...