Whether it's in real life or online. Online for me it's their name and their grammar, name to see if they're creative* (do you have an original name?) and grammar to see if they're intelligent. In real life it's their nose for some reason, probably because I hate my nose. Also their height, I want to see if they're taller than me (everyone where I live is pretty short...).
inb4 their "package" and boobs.
I totally don't this, nope, not at all, never done this, not even once
*I don't think all people without an original name are not creative, it's just an "instinct" of mine.