What is the worst personality trait someone can have? (In one word)

Dishonesty.

There should be one word for this poisonous mixture:

ignorance and arrogance

Monkeys

Terseness

:wally

Serlinesque
That covers everything else, doesn’t it?

Maybe Serliniciousness

I am with Ayesha on this one, lying.

HUGS!
Sqrl

vanity.

(with apologies to Carly Simon)

And satisfaction brought him back.
Indecision.

No, wait…

Trollishness

A word my friends made up about 10 years ago “assholitude”

Keith

"Love me or hate me, but spare me your indifference.–Libbie Fudim

Apathy is a bad one too…errr…a good one, whatever, who cares?

is “Ugly” a personality trait?

Certainty
Cordially,

The Man Who

debating skills(just to show you mine:))

hypocrisy is bad

so is someone who whines a lot - whinitude?

two-faced.

three-faced is even worse

phony.

someone who is always getting their underwear all up in a ball over nothing - i am saying overreactionary

Smug.
Makes you wanna break their self-satisfied nose.