I've never asked for a GAC at an outside window, but one time on our first or second trip, I did stop at the outside GR window at MK to make a complaint. I wasn't asking for anything, just wanted them to know. The complaint was related to ride accessibility and CMs not being helpful. Anyway, while I was talking with the GR CM, she was observing my then-husband and my sons behind me...namely the ex trying to keep the kids in check while they waited for me. We walked away with a GAC (they were actually called something else back then) much better suited to our needs than the one we had been issued the day before I side Epcot. Like I said, I didn't ask for anything. But she asked me if we had a GAC, I said yes, and she asked to see it. She proceeded to take it, go to the back, and come back with new GAC. It definitely helped the rest of the trip go much smoother.