Well, That Was Awkward

Just before closing yesterday at work, a customer came into the store on her cell phone. She was loud and angry. She went back into our uniform room, so I stayed up at the front, trying not to hear what she was saying. It was hard. Then she brought her purchases up to the front counter, still on her phone. This is pretty much how it went:
To person on phone, "Well, she's just a homewrecker. I don't know what she thinks she is doing, but it's just wrong."
To me, with bright smile, "Hi!"
To person on phone, "I know. She is ruining everything. She is such a b. . . "
To me, smiling, "How much do I owe you?"
To person on phone, "Well, she won't get away with it. I refuse to let the family go through that."
To me, smiling again, "Thank you."
To person on the phone, as she goes out the door with her purchases, "I know, right! It's just crazy. . . . . "

Number 1) It is rude to conduct a phone conversation in a public place, especially when you are dealing with a salesperson, because. . .
Number 2) we have ears. We hear things. We may be trying hard not to, or we may be listening avidly, but either way, if your conversation is private, keep it that way
Number 3) This was obviously a private conversation. It should not have been made public (please know that I changed the words of the conversation that I overheard to make it generic.) I did not want to hear this conversation, but she was practically shouting and could be heard even over our music.

I know that none of you are guilty of this, but if you know someone who does stuff like this, tell them it's just not right. Call them right now, in fact.