I think I might get my tractor just about as filthy as the next guy. About the only thing that my garden hose and regular nozzle will not get off - dried on bird poop. For that, I use a wet terry cloth shop rag. I've never used my pressure washer or soap, of any kind, on the tractor. Period
Some times I will notice grease spots starting to appear on my work clothes. Its the old grease accumulating at several locations. I will sacrifice three or four terry cloth shop rags - go around and wipe down the 32 zerk locations.