Just noticed a trend in my life. Most people that brand me "abrasive" or "confrontational" are the people that aren't interested in being honest. The exact kind of people that I don't want to deal with!
To make it clear, my default stance is "Be as honest as possible, including saying "I can't answer your question" if I don't have enough data to answer it".
Lots of people say that being able to say "I don't know" is a character flaw. It's actually a strength.