I prefer to say the truth, sometimes in a toned down version, but to me tell the truth is important.
As an answer to your question, I would say that the example of the haircut belongs to what I call PR, as it is used in companies (Maybe this word is not a very good one, but anyway...), i.e our being with other people, which I think is some kind of social mask... The fact is you never reveal yourself completely and utterly to others...So it's kinda normal...
"Oh, you've got a new haircut ! It's great, (but personally, I prefered your former one)"