When I spent the most time over sees it was the middle of the Clinton administration and I was in a small town in Germany. Most people there loved us because we were American. As soon as they found out we were American they would get very excited, ask us lots of questions about America, and we never paid for beer or cigarettes because the locals would always buy for us. There were some misconceptions. Our Turkish friends assumed we were actual horseback riding cowboys. Many also had only really knew about four basic places in America: L.A., New York, Miami, and Disney World. And they tended to not really understand just how far apart those places really are.
On shorter trips to Europe where I had less interaction I was always treated nicely, people were friendly, no one showed any anti-American sentiment, even when I was in Italy for a while during the Bush years, people were all very friendly, even out of the touristy area. We made lots of friends.
I’ve never been to Japan and it may be another matter entirely because they have fewer cultural similarities with the U.S. than Europeans do, and unless you are of Japanese descent, they won’t have to wait to hear your accent to know you are foreign. I’ve never heard a complaint from anyone I knew who went to Japan about how they were treated though.