I took a few Rustoleum nozzles and cleaned them out to keep for spares. I popped the little black tip out and cleaned in there as well. Unlike most tips there is no direct route for the paint or to clean. The black cap fits over a tiny mushroom head that has 4 slots in it. I'm guessing this is how it sprays upside down because there are 4 possible outlets?
Anyways yes they can be cleaned. After I was done I checked for more to clean. None of the cans had any nozzles because every time I need to spray I'm playing musical nozzles just to get something to spray.