Do you deem it polite to smile at someone else?

I'm realizing that this question might sound strange, but let me explain -

Just by chance I've recently come across an article answering the question "why are Germans so rude?" and was quite startled. So I did some further research and it seems to be a rather widely spread assumption, especially among (US) Americans.

Being German that sounded kind of weird to me, especially some of the experiences that people wrote down. Of course I realize that many of those might just be exaggerations or things that occasionally happened (I've come across more than enough terribly impolite people throughout my life) but a reoccurring point seemed to be that, apparently, they perceived Germans to smile very little and look offended.

Some of those opinions, I must add, were voiced in a very hateful and offensive matter (and some of them were quite obviously related to the Third Reich since allusions were made that are simply not true for Germany as it is today), but others were quite diplomatic, which were the ones causing me to wonder.

I can't really judge whether that's true or not since I'm self-taught in regards to non-verbal communication and get told to smile more often and look less angry by a lot of people almost every other day... but it has made me think. About three years ago I spent 5 months in the US and one of the most confusing things there was that so many people were smiling at me all the time, making compliments to each other (even if they were obviously not true and they would've had the chance to say something more honest, yet complimenting, to the pertaining person instead) or saying "I love you, we should hang out some time" and all these things... even people whom I wasn't friends with and who must have been aware that we'd never actually hang out (none of us ever attempted to do so). While there were some very nice people whom I still have a lot of contact to, a lot of people I met seemed to be very superficial. Superficially polite, that is.

I mean... actually all of the people do the "basic" things I'd associate with being polite... you know, saying excuse me, please, thank you or asking somebody how they are doing every once in a while.

But then again I'm currently at a University and I don't know if these manners change depending on where somebody works later on in his or her life and right now, if we're not interested in or don't like each other, we just don't talk and pretty much ignore everybody else. It's not so much offensive but very, very neutral.

So, to return to my question: Is smiling a sign of good manners (to you, whoever might answer this question)? Do you feel offended when somebody talks to you with a very straight face or if that person doesn't insult you but skips compliments?

I realize that one can't really compare the "scale" of what is thought to be polite or impolite on one country (or culture) to another's (the same goes for humour, religion and such), but I'm fairly curious.

If you've actually read all ofthis and can answer some of my questions,

thanks!

~ AJ