I think a lot has also to do with the person.
I'm not saying that everyone who complained was looking for trouble or had a negative attitude desrving such, but it would be unfortunate if the idea of 'negativity' would make anyone more keen to little things that can go either way. If you've had a postive experience, what can be better than that ?

Wherever you go, there will be a**holes to ruin your day. They'll be angels to save you from trouble. Some of the things deserve serious study, reflection, and improvement, but it shoudln't become a reason to put the whole 'foreigner thing' in a dark light. There are advantages and disadvantages, and little social skills that smoothes the interaction. The same should go for 'non-Caucasian foreigners.' Just a little different in every case.

My European experience wasn't all jolly, but doesn't make me anit-European. It is hard, though, to discern the whining and insights. I can't distinguish those in myself, either. ^___^ I hope you enjoy your positive Japanese experience next time, every time.