If they want to waste money calling a phone that will never be picked up and sending mail to a box that is never emptied, I have no problem with that. Let them waste their money.
And if they want to annoy potential customers by calling and asking for a deceased relative, I guess that's OK, too. It's their money.
It can be a pretty extreme nuisance though. In the two estate distributions I've been involved in the deceased's home became kind of the base camp to work from (being that's where 90% of the paperwork you need to work with is, plus all the stuff that needs to be distributed). So when you're sitting there waiting for calls from relatives, funeral homes, social security and insurance companies a sales call is pretty much garaunteed to piss you off.