I take "nice" to mean something very different than "good" or "kind". No, I am not a nice person. I am inclined to be an honest asshole over a nice liar. I try my best to be good, kind, understanding, etc., but "nice" is, in my books, more about manners than good acts or genuine understanding. And I generally feel that time and effort spent on attempting to be "nice" is much better spent on genuinely empathizing with and supporting people, even when that support isn't kind or well-mannered at a glance.
I like you. I'm the same way. Never met an asshole that was being dishonest. That's why I feel like I can trust them more than I can trust 'nice' people.
So yeah, I might not be nice. In fact, sometimes I'm a downright asshole. But I'll usually give you the shirt off of my back to help you if you need it.