When I do in-person retail sales training I am always shocked by the number of people who go through and think that, "How are you today," is a proper greeting. It's not. Because invariably you are hoping that customers are going to say, "Fine, and you," and they're going to say fine. That's just a place holder for an interaction. It's not good. And what even worse, if you say, "Hi, how are you today?" "Oh, you know, I've got this blister on my heel, and it's starting to bleed into my shoe." You don't want to hear it.
And so do you really want your customers to be putting up a false front when they are greeting you? No, you don't. So why ask it? It's a placeholder. And look, what's going to happen is their phone is about to go off any second, and you're not going to have that chance to develop that relationship again. So instead of asking lame things like, "How are you today," because no one cares how you're doing, don't ask it. Instead, just simply say, "Good morning," "Good afternoon," or, "Good evening."