1. Someone who is handsome, dignified and takes care of themself. Socially they will glance at people and wait until talked to. Generally this refers to a male.
2. Man who generally looks good, but isn't very social. However, person is fun and interesting to talk to. Possibly a little geeky.
3. Someone that was just met who is unexpectedly cute and interesting; worth spending further time with.
"Hey Marta, that clean shavin' guy over there with the side part. He's swaggable."
"Wow, I thought this guy would be a real bore, but he's really swaggable."
In PR circles, a person who is cool or influential enough to receive swag
Ashton Kutcher is the man, he is completely swaggable.