There is no social expectation that store keepers shouldn't talk about famous people that patronize their establishment. In fact, unless the nature of the establishment merits sensitivity, the expectation is the exact opposite.
If nothing else, it's in poor taste.
Also, if someone like a famous actor specifically asked a business not to publicise that they had frequented it, then if the business went back on that, I think they would get less famous people visiting in the future.
"Less famous people"? Do you mean people who are individually less well-known, or fewer famous people?
My favorite quote from the George Bush II years was the day he announced there would be less soldiers in Iraq in the future. I immediately pictured the same number of soldiers, but each of them shorter.