Part of the exercise was to always respond truthfully. I didn't make any distinction between omitting truth and actively lying.
I never really lied to people in the first place, but I would offer standard niceties. Those counted as lying and were no longer said. It's hard to say who was most offended. I can say that the least offended typically were somewhat antisocial themselves; those who found social norms something to analyze, rather than to follow.
Also, certainly, committing to telling the truth doesn't mean having to utter every thought that comes to mind and answer every question put to you.