I was very concerned about traveling to Vietnam the first time, and then once I got there I was shocked and relieved at how nice everybody was to me, and then one guy explicitly mentioned he felt bad Vietnam beat the US so bad in the war.
he even shrugged and did a "you know...because the US lost the war...but that's behind us. and you are welcome, it's very nice you are visiting!" and I was like ohhhh of course. i would be gracious too in his situation.