In my skydive piloting days bug build up on the leading edges was quite a problem, if only cosmetically. In order to avoid a messy clean up I would seek out a rain shower and dive through it. Did the job nicely.
Don't know anything about cavitation but I did note that the rear of the propeller always had a reddish tinge from wholesale massacre of the insect community through which I flew. The front remained relatively clean for obvious aerodynamic reasons although it seems counterintuitive.