It's a good time to be a slob. While the compilers of "World's Sexiest Men" lists and the creators of romantic comedies still abide by the notion that the fairer sex unfailingly lusts after clean-shaven, suit-clad men like Hugh Grant, evidence of a shift in the rules of attraction is accumulating. Witness the exquisite Natalie Portman taking a lovers' stroll with matty-bearded freak-folk singer Devendra Banhart, and Kate Moss running from Pete Doherty straight into the arms of Jamie Hince, the greasy-haired guitarist from the Kills. And while she's reportedly moved on, for a time Sienna Miller was dating Rhys Ifans, the slovenly Welshman from Notting Hill.

"It's maybe just a different chapter in the book of models dating gnarly-looking rocker guys," says Jessica Morgan of the celebrity style blog Go Fug Yourself. "It makes you look sort of cool when you're this beautiful girl dating a grungy guy, like you're too cool, you don't care." Still, the appeal of taller versions of Pig Pen remains mystifying.

Gordon Patzer, the author of Looks: Why They Matter More Than You Ever Imagined, has a slightly more cynical take. "One possible explanation," he says, "is that the beautiful woman doesn't want attention taken away from her; she wants to stand out."

The irony that runs through that reasoning, of course, is that going out with a guy who looks like he's been at a casting call for Homeless Man No. 2 not only doesn't make a genetically blessed woman appear more genetically blessed, it doesn't help her turn heads, either. No one's looking at her; they're eyeing the grimy creature next to her—and reflexively reaching for the Lysol.


THE GODFATHER OF GREASEBALLS
Some guys may have adopted the style recently, but Ethan Hawke has been working the dirtbag look for years. Here, a breakdown of the stringy-haired highs and lows of the man once married to Uma Thurman.

1. 1994: Scruffy
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Photo courtesy of WireImage

2. 1999: Unkempt
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Photo courtesy of Time & Life Pictures/Getty Images

3. 2001: Grungy
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Photo courtesy of WireImage

4. 2004: Toxic
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Photo courtesy of Getty Images

5. 2006: Dirty
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Photo courtesy of WireImage

6. 2008: Toxic
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Photo courtesy of Getty Images