My wife has gotten pretty creative with her shopping tactics too. One loophole I closed on her last year was when she opened credit card accounts at 3 women's clothes stores she likes, justifying it by saying they offer special sales only to card holders. Uh huh ...
Well, I eventually realized that her angle was to spread out her charges across multiple cards on different billing cycles, thinking it would dilute the bottom line. She made it about 3 months or so before I was on to her and she admitted that was her angle. We have a pretty descent monthly amount budgeted for her clothes, but apparantly it's just never enough.
I shredded all 3 cards ....