High end retail: how I immediately know my customer will be a nightmare.

I work in a sorta kinda posh boutique. My coworkers and I have gotten VERY good at spotting the a**holes.
  1. They begin a sentence/interaction with "I'm one of your best customers" or "I spend a lot of money here."
    Bitch, I know my best customers. I know their phone numbers by heart. I know their kids' names. If I've never seen you before, you are not one of our best customers. Which is fine! Just don't lie about it to try to get a discount.
  2. "I'm looking for a gift; I'll know it when it jumps out at me."
    This translates loosely to "I just want to touch/unfold everything and not buy anything.
  3. "No, I don't need to put my coffee down; I'm not going to spill."
    Well, now I'm definitely sure you that will and that it will be on something expensive and/or white.
  4. "Oh, don't worry about little Noah/Aiden/Jackson, he's very well behaved."
    Disaster is imminent.
  5. "I know you're closing in 5 minutes, but don't worry, I'll be quick!"
    Dear lord, I'm going to be here all night.