I've had the Trophy about six months now and it is never dirty! Its weird, I just cannot stand it being filthy, proper OCD about it now. If I get back from Uni and the roads have been wet i'll always give it a quick wipe down before I put it in the garage for the night. I treat it like a supercar! The red looks sooooooo good when its clean though tbf, when its filthy it doesn't look anywhere near as good!
So the longest I haven't cleaned it for is about 4/5 days, then on Sunday morning before football/pub it gets a full clean inside and out!