I carry in Walmarts all over town; Aurora, Denver, Brighton, Colorado Springs, etc... and never once had an issue with openly carrying my sidearm. Whether I am toting my Ruger P-94 or my XDM .40 compact, I never have any trouble anywhere I go.
That being said, and one I had to laugh about later, happened tonight when I was in Safeway. As I waited for the pharmacy to fill a prescription for me, I decided to walk around the store and pick up a few items. As I went down one particular aisle, I noticed a guy at the far end go wide-eyed when he spotted my XDM (replete with the extended capacity magazine) worn crossdraw on my left hip.
"Hey, is it okay to carry a pistol in the store like that?" He asked.
"It is for me. Ain't too sure about you though!"
And with that, I passed him by and ambled back to the pharmacy to get my monthly stash of pills.
Didn't see that guy again, but that was just peachy by me.
Wonder if he's still trying to unravel my answer!