No matter how funny joke I make, only a few people can catch it and other will even ignore me. 

Mostly، an awkward situation or even a 'Hate' will be generated.

No matter how boring and unreasonable other do to people in their circle, A smile and laugh Will always appear in their face.

No matter how good I try to act, it is always bad thing in their eyes. 

No matter how worse their mistake, their friends will always consider it as a good thing, or at least showing an understanding.

A connection between people is sure confusing.

For me, 

Smilling, being kind, and being polite are much easier to be done when meeting a new person than to people I have known.

Frankly, the conversation I do with unknown people feel more comfortable and well.

Why? 

Well ...

There are many reasons...

First, those unknown people don't know my weakness nor my problem

Second, I do also still not know both  their bad side and rotten intention.

Third, the 'moral & privacy' walls are thicker, the line will not be crossed. If it will, then it is only a pure coincidence for sure. 

Forth, the chance of another meeting is close to none. Because of that, We always try to left a good impression.

Fifth, There is almost no burden  shared between us. 

Sixth, the act of being good and friendly are not too complicated. It don't need many behind-the-scene reasons to do, such as act of pity, make fun of you, and asking their need. 

Seventh, Etctera.

There may be many other reasons, but I can only write this much now. 

That are my own reasons and can be different from yours.