Well, I realize this is old... but I just joined, and wanted to reply.
I am Slytherin, through and through. Resourceful, Ambitious, Cunning... and a tad narcissistic (though I honestly view that as a Gryffindor trait as well, they can often be very short-sighted).
But I'm definitely not a vile person, I just know what I want :)
I assure you,
You will never be able to find someone who is a bigger Snape fan than I am. lol.