The other person will smile and laugh, and they'll exchange a couple other words, and then be on their way.
What do you think my wife is looking for that's a red flag?
But in America at least, it's not usually bullshit or false. It's not a means to an end. I will compliment servers and cashiers and receptionist just because it makes everyone friendlier and we all enjoy our brief interaction more than we would otherwise. It would be nonsensical to say I was using them. For what?
I am aware that there are cultures out there where nobody does this and it is viewed highly with suspicion. It just makes me very happy I don't live in one of those places.