What: That once unwelcome re-growth is suddenly trendy.

What the experts say: Colorist Dawn Tracy of Byron Salon in Beverly Hills says in a recent Los Angeles Times article: “It’s a look that says, ‘I haven’t bothered with my hair.’ It’s sexy and looks undone.”

What we say: Good for Tracy for getting blond clients to cough up $125 to have her hand-paint dark highlights onto their roots. At the Frederic Fekkai salon on Melrose Place, ...