People often use being "honest" or "blunt" as an excuse to have poorly developed interpersonal skills.

It is possible to be honest while being tactful and it is also possible to speak your mind without being rude or hurtful. Honesty doesn't have to be accompanied by rudeness, bile or excessive judging.

People who describe themselves this way are generally bad at reading social queues and don't understand how to conduct themselves around other people.