people hate americans because lets face it, nobody likes the generic big guy. see rome, see the han, see microsoft, see mcdonalds, see the brit empire, see walmart, see naruto and other popular commericial things

and also, america is pretty conservative compared to most industrialized countries, especially asia where morality is only a convenient buzzword (no offense of course, im asian, and asian countries do just fine without morals). We all know how we feel towards people who are more conservative than us, and not everyone can hold back that desire to say "you're fucking nuts"

that hate pretty much just snowballs into a tradition, half the teens here in canada "hate" the americans, most of them have no idea why they should