Well, you can clean yours to your hearts content, then.
My eXmark gets chunks scraped off when the blades get sharpened a couple times a year, and the first one lasted 25 years, and only got traded in because the clutch finally went out, and I got a excellent trade-in on a new Lazer Z, the dealer sold my old one within a week after he replaced the clutch!
I think keeping the engine clean and properly lubricated is much more important than keeping a deck spotlessly clean.
By the way, I mow between 8-12 acres each week.