For me, it's not about 'being honest at all costs.' When I'm in a situation where I am forced to respond, and I know I should lie so I don't offend someone, I feel this huge ball of stress begin to form inside me. I get overwhelmed entirely. In my head I'm thinking, "What should I say? If I say X he might take it this way, but if I say Y he will take it this way, maybe Z, no no he will take it THIS way." And I go down the rabbit hole so to speak. There are so many variables and so many repercussions to telling a simple lie. If you are polite they might talk to you longer when all you can think about is getting away from them. Or if you divert the conversation they may think you are self absorbed. Etc. For me, honesty isn't about finding an excuse to insult someone. It's just so much easier. If I want to be around someone I tell them. If I want someone to go away I tell them.
Shameless, I wish EVERYONE were like that. Just think, no more trying to decipher clues to finally come to the conclusion that someone who tells you they like your shirt doesn't give a crap about your shirt they just hate you. Life would be so ... quiet.