@Fatdaddy aluminum does not clean like vinyl. You’ll be there a month of sundays trying to get it cleaned when it’s typically something that’s in the coating and won’t come off.
If they were my friends I’d get them a gift card to Sherwin Williams. If it’s not a friend, I’d walk so I don’t have to pay my deductible for a job that is worth less than the deductible to begin with. Then you’re out $300 from a botched house wash and $500 for your deductible.