[jacquesm]

I think it revolves around 'acting nice' vs 'being nice' but the words escape me to articulate the difference any clearer than that.

[palebluedot]

I think I understand what you are saying, and you are right, it is difficult to find the exact words to express it. But I think you articulated it well. I just wanted to highlight that my intent was not to promote the idea of being artificially nice :)

[mtm]

I think you the word you're looking for is 'sincerity'