Great for crowd control! No Police overtime required!
I just blow off various wing mowers that I have with compressed air. On my Cushman, I blow out the rad, oil cooler and engine compartment as well. This suffices and keeps those nasty organic juices from eating your decks. At the end of the season, I pressure wash or steam clean equipment and put to bed. Grease them and run them a little in case water got into bearings.
The only exception is, if I got rained on or got into swampy/muddly areas and then usually just pressure wash the machine and blow it off with compressed air.
Nothing irritates me more then seeing someones grass cutting machine covered in old grass, especially parked over the winter!