Those cards are the lowest form of marketing...but to some degree they work. I got a lot of them when the DC region started to boom in the 80s. I used to have my own business helping people sell their businesses. It's sort of like being a real estate agent for business owners, but you gotta keep it discreet because of the damage that may be done if word gets out that someone is selling that business. It was interesting. One of the recommended tactics was to send out similar cards..."We know someone who may be interested in buying your business!" Uh, no we don't. We are liars. (I refused to do it.)
We have been hounded by real estate agents since my MIL died. It seems like we are still getting one or two calls a day about listing her place, and postcards every week or so. I don't know how they know that my husband is her executor or how they got our address/phone number. So aggravating.
Start with the obits."Survived by..." And the Estate Administrator is public record at the county. Real estate agents and developers have inside connections with a few of our civil servants. It's scummy.