Personally, I think Paris Hilton is a waste of space.
I find it appalling that she's as famous and popular as she is if she's as dim as she comes across in interviews; if she's not actually that stupid, I have to wonder why she feels that persona is necessary. (I've read that Jessica Simpson claims not to be as dumb as she's portrayed in the media and that she plays dumb because "that's what boys like." Quite frankly, if men are intimidated by your intelligence, perhaps you ought to be seeking out different men?)
I don't necessarily think she's as promiscuous as she's made out to be; if anything, she seems to be something of a serial monogamist (although I suppose her behaviour on The Simple Life might suggest otherwise). I don't think her sex tape makes her a bad person, just one who trusted foolishly in someone and has paid the price for it -- if anything, however, that tape has done a lot to make her more famous.
What bothers me is how callous and indifferent she is to the world around her. She spends a small fortune getting her cellphone (or PDA or BlackBerry or whatever) decked out in sparkling crystals while people go hungry, unsheltered and without clothing. I realize it's her money and she can do whatever she wants with it, but I still find her frivolous lifestyle horrendously pointless and sad.
What frightens me the most is that she is a role model for young women, and that her popularity makes it acceptable to be ignorant of the world around you (in one recent interview for her upcoming movie Hottie or Nottie, she says she can't remember who produced the movie, all she knows is that she's the star), that it's cool to dress like a tramp (yes, women should be allowed to dress however they want, but they need to be cognizant of the image they project, and I don't necessarily know that a thirteen-year-old girl emulating Paris Hilton has the maturity or life experience to realize this), and that you can happily disregard the needs and feelings of the people around you without any negative consequences.
And that is way more thought than I typically give towards Paris Hilton!