Yeah .... I'm one of those ..... I apologized to my mechanic for bringing him things that I f*^#ed , said not to worry, I'm not the only one.
I've got a pretty good local mechanic. He's worked on my cars since I was 16. He's the only one that's ever quoted me a price and then charged me less, so he earned my business. These days I barely see him since I do most of my own service. BUT he'll still help me out since I send him a ton of business. Most of the time if he does something for me less than $50 he'll just say to square up with him next time. And he knows I'll drive myself crazy reminding him because I hate to owe people money.
There's been a few times I've called or text him just for advice. "Hey I accidentally broke off the bolt that holds one of my coils down....and I've tried to tap it and broke that off as well. What's the safest way to get this thing to you without effin it up more?" There's been a few times I'm sure he's spent more time than he charged me for. BUT, he knows my whole family, half of my friends, and what they drive. So it's washed out in the end.