Erm - I think ... hair and make-up on their own, it's very hard to make it 'slutty' because you pair it with a conservative outfit and well - it just isn't. Maybe a bit trashy though.
But otherwise - when girl have those really, really, pale lips, and then a much darker lip liner on. Looks right out of a p*rno.
And I suppose extreme smokey eyes, so extreme they're not really smokey anymore - just lots and lots and lots of eye make up that goes right up to the brow with a bright color (insert blue here (but I'm sure other colors would work too)) and then lots of thick black liner. LOTS. And clumpy lashes.
And very badly drawn on eyebrows.
But like I said - I don't think any of that on its own would look 'slutty' more ... bleugh. But put it on a girl with a fake tan, skanky outfit and plenty of hair-extensions, and yeah - it would probably look slutty.
Yes, I think so. Well, more trashy than slutty. I think slutty is about behavior . But your style can make you look classless and tacky.
Makeup: poorly applied or super over-the-top makeup can give you that 'trashy' look. Like, I really, really hate Christina Aguilera's makeup style for these past few years. There is just wayyy too much going on. Here are some examples of what I consider to be trashy/slutty makeup: linklinklink
Hair: sometimes teased hair can look terrible, or poor dye jobs. I.e. roots showing (non strategically) or Amy Winehouse-styles.
What makes a person seem slutty or not isn't their makeup or their hair, it's the attitude. In the pictures linked to below, the girls don't look slutty... they just look trashy and/or plain ridiculous.