Getting my scooter fixed

Occasionally I hear foreigners complaining about getting "the foreigner price" for stuff, like getting stuff fixed or buying stuff at the traditional market or taxis. Honestly, this stuff is all so cheap compared to back home that I seriously wouldn't care if they marked it up 20%, but I really think this has never happened to me. If anything, I've found people go out of their way to be helpful- like once in Taichung the taxi driver got lost and didn't make me pay the full meter; on the occasions that I buy meat and veggies at the market they usually give me free stuff, etc.
I've mentioned before that just getting them to fix stuff- like shocks or springs or whatever, and speedometers- that aren't strictly necessary to the functioning of the scooter is kind of tough. I guess they don't want to rip me off but I guess scooters are pretty non-luxurious to start with, so I don't mind paying a little extra for "luxuries" like a working suspension.
The scooter guy I go to now, near my apartment, is so funny. He always insists that I stay and then shows me piles of crud that fall out of certain parts of my scooter, or some barely-hanging-together part that only becomes apparent after he's unscrewed 3 layers of innards, and says things like "It's so dirty!" or "If that would break, it would be really dangerous!" I've found the best course of action is to act really shocked and thank him for showing me. This time I did get him to let me leave with the promise that I'd come back later. I told him, Whatever there's a problem with, just fix it. You're very skillful, I trust you. He was like, you don't want me to call you and tell you what's wrong? No, it's OK, I said. Just call me when it's done. He did save the old parts to show me. I'm like, charge me extra, I don't care, just don't show me all this stuff! Haha. Cause seriously it's so cheap.