FBOs typically monitor the ground control radio frequency, so that when you request taxi to that FBO, they know you are coming and can be ready to wave you in. Otherwise they just see you trudling onto their apron and zip out with their little flashlights to tell you where to park.
Some marshall you into rock star parking right in front of the door, and then tow your airplane to an appropriate place after you have unloaded. Like valet parking, except you don't need to give them the key, just leave the parking brake off. Others marshall you directly into a parking spot, usually marked out with a T on the ground, with your fuselage over the upright and your wings along the crosspiece. Then they usually offer you a ride to the door.
Not long ago I followed the line guys' signals to park in one of these T-marked spots, put on my parking brake, and shut down. They chocked the wheels and as I locked the back door I asked them if they would need to tow the airplane. "Nope," said the guys. "It's going to be fine right there."
"Good," I said, "Because I left the parking brake on."
When I came back, the airplane was not where I left it. It had been towed. With the brake set. This is the sort of thing that makes pilots unhappy. I went out to the airplane and into the cockpit to release the parking brake. Then I crawled underneath to inspect the brake pads. They had been new. They didn't look excessively or irregularly worn. This could mean that they didn't grip, or that they gripped all too well. I went inside and explained what had happened, and asked for the airplane to be towed forward a little, so I could inspect the underside of the tires. The line guys who came to help were different, the other had gone off shift. They thought it was odd that the airplane had been towed and were trying to work out who it had been.
I think I have some pictures of what happens to a tire that has been moved forward while locked. Sometimes this happens if a pilot lands with his or her feet on the brakes, or locks up the wheels by braking heavily after landing. I really don't want to see this on my airplane.
The towing device they have is different from what I consider normal. I'm used to a towing bar shaped like a giant tuning fork. The fork hooks into either side of the hub of the nosewheel, and then the wheel is pulled along the ground. This device actually goes under the nosewheel and lifts it up. They tow it forward inch by inch and I'm watching for a flat spot to emerge from under the tire. But there's no damage. The tire shows no sign at all of having been dragged. "Phew!" I say. "Thanks for helping me check that."
A manager has been alerted and comes up as I'm discovering that everything is okay. He apologizes, recognizes that this should not have happened, and explains that they have a system where not-to-be-towed airplanes get a different colour chocks than ok-to-tow airplanes, so he is going to investigate what happened here. I accept the apology. It turns out that no harm has been done, so I can relax. I guess the brakes released. That's why you're not supposed to trust parking brakes overnight.
I'm a kind of stereotypical customer in that respect. I can be mollified by someone who simply treats me with respect and acknowledges that I have been wronged. If the tires had been damaged I probably would have insisted on at least free labour to change them. They had their own shop. My airplane tires are actually pretty cheap, and I'd done a lot of business with them. And I would have accepted some kind of compromise to that effect. So I leave still a happy customer, just a more watchful one. I can buy a DO NOT TOW tag, I imagine. Or just not set the brakes.