To avoid a shitton of quoting and such I'll just give one related statement.
It's not so much that certain cultures are completely impossible to be around, it's just that a lot of people in general are complete idiots and amazingly difficult to tolerate. Given, if any person of a certain race or culture whose actions reinforce any the negative stereotypes of their people, I will not hesitate to call them out on it.
A perfect example of such would be my Mexican neighbors who constantly blare their shitty polka music out their truck's speakers with the awful bass system from seven in the morning to nine, sometime even ten or later, at night. Everytime that happens, i.e. every damn day, I instantly think "f*cking Mexicans" and try to continue going about my day. Of course, that does not mean I am condemning everyone with dark skin and a funny accent; no, I'm just really annoyed with that set of people at that time and wish their truck would sudden set ablaze. Meanwhile, I have a good deal friends of that same race, one of which is a girl I've grown up with since kindergarten, who are all great people to be around. They know how the hell to act around other people and get along with them, just like the rest of us. The same can be said about any group of people. I could give more examples, but unless you're a slow child who has spent most of his life locked in the basement, you should have gotten the point by now.
tl;dr certain races of people are not assholes, people are asshole and happen to be part of certain races
If morons would stop being perfect examples of all the reason their race were given a bad rep in the first place, generalizations and stereotypes would have died years ago.
Go find someone else to blame.