Are they designed to be "crushable" threads? That would be a new one to me but who knows, maybe something new is on the market. Anyway, why not go ahead and clean both sets of threads.
BTW: an old Navy
machinst taught me something a long time ago and I have not forgotten. When mating thread componets, turn the one piece opposite direction until the threads marry. The click, whether heard or felt, will tell you the two are properly mated and ready for torque.