Fat, dumb, ugly, annoying. One or more of these words applies to you, does it feel good knowing that? Though we've never met are you glad that I was honest with you or would you rather that I just kept that to myself?
No one wants to hear the actual truth. What's the first thing you do when someone says something about us we don't like? We try to convince them that are wrong. If you thought that I hurt your feelings and think I'm an asshole, you would not be wrong in that feeling. No amount of me logically explaining my behavior is going to make you think "Yeah, I guess he's not an asshole."
The only reason people will claim to admire honesty or to be "brutally honest" is because they want to excuse themselves from the horrible things they are about to say to you. In a perfect world we could all be narcissists surrounded by a bunch of androids, built to pay us flattering comments and accept verbal abuse. Unfortunately, the world is not perfect and people don't want to hear the truth especially in the vile, offensive way in which you present it.
Even on occasions when I say I want the absolute truth, I still want a softer version. I want to hear: "Yeah, unfortunately we're going to have to lay you off due to cutbacks." I don't want to hear "We're firing you because you are a lazy inept piece of shit worker who brings down the productivity of the company whenever you are here." Both of these statements achieve the same result, but one is less hurtful. Even if my wife was having a sordid affair I'd rather her say "Yeah, me and my friend Thomas were just exchanging massages, that's why we had our clothes off."
From what I know about society everyone recycles, no one watches television and no one eats fast food. Yet streets and garbage cans are littered with bottles, American Idol consistently gets 30 million viewers and there is a fast food chain of every name in every town. The reason we claim to recycle without fail is there is nothing but a negative connotation carried with not recycling. If people say that watching television is bad for you, then you project the image that you don't watch it. Fast food is unhealthy and you don't want to be seen as unhealthy or fat, so you deny it. Let it be known that your individuals reflections on each of these things mentioned do not concern me. These are merely rhetorical to drive home the bigger point. The bigger point is that people are dishonest when the doing or not doing of something carries a stigma.
If we are honest with ourselves we like a little dishonesty spliced in with our honesty.