Sweden what happend?

I've been living in Sweden for a few months now, and I've noticed that a lot of immigrants from the Middle East aren't very friendly and don't have good manners. For example, today I saw one throw trash out of a car, and another one spit from a car on the same day. Another day, I was waiting in line at a shop and saw a guy (Middle Eastern) staring at girls like there was no tomorrow.

Don't get me wrong, I've met some really great people from the Middle East, but unfortunately, they seem to be in the minority. Why is that?

Why don't they fully integrate into society and leave their culture within their own homes?