It doesn't bother me when they check my receipt. I understand that the very visible existence of this security procedure undoubtedly prevents a lot of pricey electronic stuff from walking out the door...

But it would bother me a lot if I knew they were doing it because the shopper was black or hispanic...

I was once shopping at another store, just browsing around until I decided to leave. And I absent-mindedly walked out the front door holding an umbrella in my hand, which I had forgotten to purchase...as I was walking away in the parking lot, I suddenly realized my error and I rushed back into the store and went up to the cashier to pay for the umbrella. She gave me a very dirty look, but then took my money for the umbrella. I left the store, thanking my lucky stars, and thinking, "Man, if I didn't look so white, I would be so busted right now!!" And, hell, it's true. Some security guard would have come out of no where and tackled me before I got 5 steps outside the store...