I've always had the belief that it is better to tell someone it is NONE OF THEIR BUSINESS than to LIE TO THEM - but some situations are so far from the norm, that special rules must apply. If a small lie lets someone go about life feeling better about themselves, then I'll gladly stretch the truth some.
Again thought, sometimes it is a matter of opinion too: my wife came home with what I thought was a hideous haircut one time, she was obviously boasting it toward me, in her mind really loving the look - To me it looked like three birds and ha fight on her head and they all died right there, but I sure wasn't going to tell her that. If it made her feel happy, thatn my feelings for her outweighed my perception of the truth. Then again, who is to say that it wasn't ME that was wrong!
When it comes to the forum though, I always do my best to keep the members informed with the most accurate info I have - good or bad, I do the boss thing. In private messages, I speak openly and try to resolve issues or show the member the door. So when we lie and why we lie really has purposes that can't be answered in a yes or no format.
At the end of the day, it is about feeling good about yourself and how you have made others feel.
In the outside world: work, dealing with strangers or at least people you owe to, then you have more room to tell them it's none of their business, and I don't mind doing that one bit.