Honesty is different than bluntness. Bluntness is the intensity of how you say what you mean. You can be a little honest and very blunt at the same time. A good critic should always strive to be honest. If you're not honest, you're not a good critic. But you don't have to be blunt to be a good critic. When a critic is very blunt, people assume he's being rude, and he might very well be. Honesty isn't about etiquette. Bluntness is. With a poet friend you can be blunt, and they probably will forgive you, and still want to hang out with you on Friday night and drink margaritas and watch Buffy reruns or Dollhouse.
I pride myself on being a critic who is honest. Honesty is a good thing especially if you have the right friends, they forgive you if what you say hurts/annoys them. My friends are smarter than me, which is deliberate on my part. When you have smarter friends, they quickly figure you out and know how your mind is troubled. Once my partner and I got into a fight, and I got hysterical, and he said, You are crazy and insincere. He knows who I am. I love him.
Sincerity is a different thing altogether from honesty and bluntness.
A well-intentioned critic may panic that the honesty won't be noticed, so they freak out even more and become more blunt. You can't use bluntness as a vehicle to become more honest and therefore noticed. In fact, if you try it, it may have have the opposite effect, especially when it reaches people you may not know. All people will notice is the bluntness and no one hears (understandably) the desire to be honest. No one will hear the striving to talk critically and sometimes even affectionately. No one will hear that you try to be honest to disclose something like love to certain poems and people (and sometimes even other posts on other blogs.)