Here's the letter I sent to Flying J. It's pretty poorly written due to having to use on of those contact pages instead of my regular e-mail, but it's workable.
At two separate locations, Tacoma, WA and Russelville, AR, I was politely asked by one of the managers to leave due to my lack of footwear. As a member of the Society for Barefoot Living, I spend virtually my entire life without shoes, wearing them only when there is a very real and clear danger to my feet. There is no health risk associated with bare feet, nor is there any statute prohibiting people from not wearing shoes. I realize it is possible to step on something and be injured. But, it is also possible to injure a foot even while wearing shoes. It is also possible to injure other body parts, yet I've never been questioned about protecting them. For instance, one can easily bump their head or cut their hand, but I've never been asked to put on gloves or a hardhat in a store. I make it a habit never to return to a store that has hassled me about my lifestyle. Given that I've experienced this at two locations, I'm assuming it is a corporate policy and will no longer use Flying J facilities. I realize this will hardly impact your ability to pay the light bill, but I have spread the word to the other members of the SBL. We use our network to find barefoot-freindly establishments so we know who to do business with and who to avoid.