Lack of honesty in dealing with themselves. If they are not honest with themselves about their life, they cannot be honest with you.
Sorry, what did you say?
I do not think any one trait can be branded as a "worst quality." It is the whole package that it comes in. Just because they don't acknowledge what you said, doesn't mean they didn't listen. Different people have different social backgrounds and have different ideas on what "active listening" looks like.
I'm sorry, what did you say?
I think apathy is the worst. People who don't care about anything are basically wasting their humanity.
being rude, being dishonest.