I make a fortune from repairing the decks of customers who pressure wash their mowers and particularly when trying to remove accumulated clippings from the deck.
So I blow with a very long handled air duster and sell these to my customers.
Even then I can oft shift lumps of paint if the deck surface has been compromised.
Every one who has recommended pressure washing is either a mechanic or professional lawn care person.
The only part I pressure wash is the engine only if it needs degreasing.
Just did both spindles on a brand new Cub ZTR because he did not run it after he washed it.
Toros with wash out decks seem to do bottom spindle bearings regularly for the same reason.