Mom said "I love you" to the clerk at the store. She is overly friendly to strangers, but keeps no friends. How to deter this behavior?

She has never met this woman (the cashier), and just leans in towards her and "coos" "I love you" to her. I was flabbergasted, said lets get going mom, but she continued telling this woman what a beautiful face she had and other flattery that she uses to create these "golded moments with strangers" is how I refer to it. It can be quite embarassing, and some people don't want the attention/invasion of their personal space. She gets physically close to them, and one guy actually barked at her to get back while at the grocery check out. Others find her quite charming. She does not really listen when having a conversation, and doesn't try to get to know people, that's why no real friends. She just wants these one time connections with random strangers that she accosts. Other than encourage her to join a group, which so far she has dropped out of every one we've tried. What can I do to get her to stop this inappropriate affection? She will also hug people she just met at the store often kissing them on the lips. This vocalizing of I love you to a stranger is a new issue for us. She has always been a attention hog, but that never really bothered me, as it was harmless. Sorry if redundant, just writing this off the top of my head and can't really see what I've written to proofread, but I'm sure some of you have experience with this and can offer some ideas or just spme support. I've posted here before, maybe some of you remember me from before. Anyways, sometimes I think I am going crazy with her.... Ideas?