The slogan "You can never be too thin" isn't something most people agree with, and for good reason. People are already taping pictures of Nicole Ritchie and other sometimes dangerously thin celebrities to the sign. I honestly think it is the dumbest method of advertising a product I've seen in a while.
I think some ad guy was not well plugged in to the public's concern with the anorexia seen on many models and celebs. The article says they are taking the billboards down. Appropriate response; the sooner the better.
Definitely a poor choice of words. I think it was clear what they were trying to do, though.. But the sad thing is there are so many people out there that would read into it the wrong way.