True inspectors don't wear uniforms, but I don't think you have anything to worry about if you run into one. That is unless you take your jacket off and start threatening people with it. It's the employees with the jackets that worry them, not the customers.
I go in like gentleman. I sit in the parking lot for a few minutes, just so they know I'm not a threat. Then upon approaching the door, I ask, "Is it ok for me to come in?" Once I get the green light I approach the waiting line slowly, then when they call me to the counter, I rush forward to deliver my package. Then I pay and leave.