If by ‘catty’, we mean ‘says snarky things about other people,’ I think it depends on the person and the situation.
Sometimes people have catty tendencies (I hate using this word, but I can’t think of a fitting substitute), but it doesn’t dominate their personalities, or they honestly mean it in jest.
I was talking to a guy the other day who made a comment about how this girl ‘always has to dress so slutty’ and I just completely ignored it and changed the subject (though now I’m wishing I came to her defense). I’ve also had friends who made veiled insults about other people and I just brushed it off. They had enough positive attributes to make up for it.
Besides, everyone has their moments. What’s one person’s sly joke is another person’s nasty comment. Sometimes I say things that sound a lot nastier than I intend them to.