I'll start with my "best"...Although that would be to do with my other hobby, flying model aircraft. I was killing time in a small town during a holiday break and as usual in the UK, it started raining, so I nipped into the nearby church which was holding a jumble sale. On one of the tables, burried under a pile of the usual junk some elderly ladies were looking through, was a small box i recognised at once. To my good fortune, it still held its original contents, a vintage model airplane engine, worth about £150. When I asked how much they wanted, I was told they didn't know what it was and I could have it for 50p if it was any good to me....RESULT!
My "worst" would have to be building a model for someone as a commission, which I hated doing because the subject matter held no interest for me, only to find out later that he'd entered a couple of local shows with it as his own work! Ok, I got paid for it, but he was getting the credit. That was way back in 1977 / 78, I was only 17 and just let it go. I still sold stuff through my local hobby store after that, but it took the gloss off the hobby for a while