When I was thirteen, my grandparents took me to Greece for my birthday. This was, of course, completely awesome. Except that every time I had the opportunity to order Greek food, I chickened out and ordered souvlaki. When I got home again, I felt like a schmuck because I had wasted a rare opportunity, and I swore that I would never make the same mistake again.
(For my fourteenth birthday I asked my grandparents to take me to a Greek restaurant and order for me. I remember eating avgolemono soup and moussaka for the first time.)
I have done pretty well by my oath. I've been a lot of places and eaten a lot of stuff. Not all of it was good, but most of it was, and some of it was great. I went to Hong Kong in 2001 and ate everything, not just Cantonese food but also my hotel was having an exchange program where a bunch of hotel chefs from Budapest came to show the Hong Kong hotel chefs how to cook Hungarian food, and there was a Hungarian buffet every night, which was also pretty wonderful. I went to Taiwan in 2003 and ate everything and the only bad meal I had was in a crappy restaurant across the street from the bus station in Hualien. And it wasn't because they were serving anything surprising, it was just because they were bad cooks and their crappy restaurant was dirty.
There are only a few missed opportunities of the same sort that I continue to regret. One summer I was working in southwest Illinois, and after work I went for a drive to see if I could get to the Indiana border. I drove to Lake Carlyle, took a nap in the front seat, then started driving around county roads at random. At some point I passed by a little restaurant in the middle of nowhere away from everything else, and since it was dinner time, I went in.
The special that day was chicken gizzards, which I've never had. But I wimped out and ordered a hamburger. Dammit. I was having an adventure, and when the adventure offered up a plot twist I said “No thanks, I've had enough.”
Another episode, not as bad, was when I was on my road trip last summer to drive around Chesapeake Bay. One day I stopped for lunch and got soft-shell crabs, a regional specialty and also a favorite of Placido the Octopus. I asked if the restaurant served Smith Island cake, also a regional specialty, the official dessert of the State of Maryland. They did have it in several flavors, including caramel, but no chocolate, so I skipped dessert. That could be worse. If I really want to try a Smith Island cake I can probably mail-order one. Or go back to Maryland.
Those lost chicken gizzards really bug me. Maybe I wouldn't have liked them, but they would have had to have been pretty awful to have bothered me as much as the ones I didn't eat.
 I did not make it to Indiana, or even close. Lake Carlyle is only about 30% of the way to Indiana. I still haven't made it to Indiana. Someday, though!