An honest person communicates in an unadulterated, trustworthy manner.
Those who claim 'Jesus is Lord' yet refuse to obey Him are considered 'liars' ... The one who says, “I have come to know Him,” and does not keep His commandments, is a liar, and the truth is not in him. (1 John 2:4)
And those who purposefully misrepresent or misinterpret Biblical truth are considered 'liars' ... Do not add to His words or He will rebuke you, and you will be proved a liar. (Proverbs 30:6)
A true follower of Christ expresses his honesty from a spirit of gentleness. He is motivated by love, not an obsession with relaying accurate information.
You might think that expressing everything that comes to mind is 'praiseworthy transparency', but it is actually a vainglorious display ... When there are many words, wrongdoing is unavoidable. But one who restrains his lips is wise. (Proverbs 10:19)
One more point ...
Your prayers should be open and honest as well. Speak candidly with the One who knows your heart and loves you beyond measure.