I keep my pto shafts greased.. but then as soon as I remove the pto yoke, out comes a clean napkin that I rub any debri from the shaft, re-grease lightly, and then replace the pto screw in cover. When i need to use the pto, the screw on cover comes off, and I have a nice shiny clean shaft.... I do this every time.. has worked great. I find that the dirt and debri do stick to the grease.. but that a good napkin or towlette gripped firmly around the shaft at the base, and pulled forward removes it all...then ya just re-grease.
Spray brake cleaner cleans the female yoke just fine..
Soundguy