Is it considered weird to be rude/mean in the U.S?

[who?]

Not really there are rude people all over the place. The vagrants were most likely homeless people. Here is a very brief explanation. Up until the 1980's insane people & troubled people (the kind that are not capable a caring for themselves but are capable of walking) were kept in homes or hospitals for mental patient's. Turns out many of these homes were not taking good care of them and some were abusive. Society decided that this was not what we wanted and closed many of them. The idea was family care was better. We also made it harder to lock someone away for treatment against their will. The problem is many homeless people have distanced or don't trust their relatives, since they are ill its impossible to hold a job or pay rent. Yes the homeless can be rude, its more about their health than something you did.
OP where are you from?

The federal law about moving the mentally ill into the communitys and provide for community mental health treatment was passed in 1963 http://en.wikipedia.org/wiki/Community_Mental_Health_Act not the 1980s.

 

[Slew Foot]

so liberals tend to be a bunch of assholes. makes sense.

 

[norseamd]

so liberals tend to be a bunch of assholes. makes sense.

Minnesota and Wisconsin are liberal. And Texas is very conservative.

 

[MongGrel]

It's all pretty subjective of course.

I've been in spots you can walk a mile and it will change a lot.

 

[hans007]

Well, I wouldn't call San Francisco as representative of the U.S. or even California but, people do tend to interact more politely (according to our culture) than in other countries.

Sf is very not representative of the us. People are very cosmopolitan there and its considered the most European american city by many. I don't think people are horribly mean in other cities but Los Angeles for example can definitely be less polite.

 

[Markbnj]

When I went to the S.F, I found the people to be pretty nice. The rude people were some of the vagrants that started to go on a profanity spree towards me... for some odd reasons.

That's just San Francisco. They have a peculiar breed of aggressive and batshit crazy homeless folk there.