Well most criminals look for easy prey. The last thing they want are extra holes being put in them vs. their intended victims. I speculate, as a 7/11 stick-up professional is not avilable for me to question; that if he/she see's a armed person in a store prior to entering, they will simply go down the road. If he/she notices once inside prior to announcing / displaying their weapon, again they simply leave.
If you're in a CCer's fantasy world, the ideal situation is to have a OCer with you in every quickeee-mart. This way he/she can get shot while you fumble for your pistol under your garments, then wait for that "right time" to go on the attack. Of course this is just that,their fantasy. Rambo, John. J, wannabe's.