I think that's a really odd position. I'm more inclined to shop at places I can pay with my AmEx, simply because I like to accumulate MRs.

Do you think, given the choice, stores would rather a) not have my business at all or b) incur a slightly higher discount rate on my purchase?

By the same measure, would you think that store owners think 'oh my God, another ........ costing me money' when you pay on a Visa credit card as opposed to using a debit card? Or, as usual, is the ire reserved for American Express?