A wise poster on here (can't remember who) said that custies tolerate us as a necessary evil; another said that custies don't expect good social graces from a windy.
We can play both to our advantage - and if they want us to tolerate them they must tolerate us!
Or like Tosh suggests bore them with a long explanation or go on step further - tellum you're a buddhist or a jw and they'll soon hide and let you get on with it.

Then you put a bill through and get paid on line!
BTW - I give them a written rain guarantee which I clip to their receipts when working in showery conditions.