I hate hearing that. Hate. Hate. Hate.
It’s an understandable reaction, but no. No, that’s not what it means. Stop doing that. Or if you do it, tell yourself you’re wrong. If someone isn’t attracted to you, it means that he (or she) isn’t attracted to you. That’s it. Don’t put mean labels on yourself! Especially don’t do it when the situation doesn’t even imply it.
Think of your own preferences. How many times have you thought someone was cute or sweet but “not your type.” Basically, you’re not attracted to them, but you could see why someone else would be. If you turning them down made them call themselves ugly, you’d be horrified. That wasn’t what you meant at all.
Well, that applies to you, too. Maybe you’re not the person’s type. Maybe they’re already into someone else. Maybe they just aren’t ready to date right now. That doesn’t make you ugly.