The only way we end this type of treatment is to say "Yes, I am done shopping. I don't shop at places that treat me with such disrespect when I'm trying to give them my business. You can put all this stuff away, we'll just get it from one of your competitors. Oh, can I have your business card so I can register a formal complaint?"
Covering it up and then finalizing your purchase just reinforces their bad behavior and treatment of open carriers.
I realize having the wife with you is the hardest part about it. My wife doesn't always like it, but we have an agreement that if we're kicked out, we're kicked out, and will refuse to comply with anything they ask (other than to leave).