So for the sake of $2.50 you did a real good impression of an arrogant foreigner . Hence the well known term "Ugly American." Such an apt description .
at no time does the above poster indicate that they are foreign (let alone American). In fact, contextually you could conclude the poster is just as likely to be Chinese as foreign.
Your comment does a real good impression of being judgemental without facts. Hence the term "jumping to conclusions"