I usually only mention a resemblance to a celebrity if the celebrity is quite good looking. We once had a waitress who looked like Trisha Yearwood. Someone at the table asked her how often the resemblance is mentioned to her, and she said several times a day. She said her family agreed but she just couldn't see it herself.
I have regular contact with a person whose name is the same as a notorious person (notorious for a crime, in the USA you'd recognize the name). I have never mentioned it, and never will. There's no need to remind this perfectly nice person that there's a nationally known criminal with the same name.