First impressions

What's your first impression of a persons sun sign? When you find out their sign do you feel it fits the description you've seen or heard about?

I seem to pick up on certain signs easier than others. I can typically tell if someone is an Aquarius or a Scorpio, or a fire sign. But with other signs I have trouble reading them. Like, I never meet a person and think their a Libra... Don't know why though