The problem is that the one pictured (Louie) is getting old, and hosing him would probably see the end of him. That wouldn't make me at all popular. However the younger one (Merlin) is fair game and usually gets the garden hose if I'm quick enough. Don't see him on the roof very often these days .Get one of those super soaker water guns, cats learn by association i.e sleep on car roof wet pussy, sleep on floor dry pussy.