I like her style its not slutty or trashy. I see her looks as more like a rebel or a "bad girl". Trashy is when you look like Amy Winehouse, Lady Gaga, Little Kim, Fergie (like in this link:) link
or how Britney Spears used to dress when she went out in public with K-Fed. And how these women dress in this link: link
If you have a similar body to Ke$ha then by all means go ahead and make your hair blonde and curly and get your nose pierced and dress like her. But don't get anymore piercings. Piercings on blondes usually don't look good and they seem to only look good on the nose.
See its hard because she might be rockin some hot gear but I don't know because I don't think that she is cute at all lol, I think that's why she wears a lot of sunglasses most of the time. Maybe on a cute girl her style is hot