My general response to that sort of thing, is to just smile and tell them that I would be happy to let that acclimate. If asked what I think of the idea, I explain that there really isn't any reason to - but if they have reason to believe it should I am more than happy to do it to their parameters.
And if placating them is going to put a serious (i.e. cost me time/money) crimp in the job, then I explain that doing so will mean additional cost to the homeowner.