I saw an ad today for "a cure for white teeth.. ."

edited for typo

Is that like "a cure for beautiful eyes?"

Funny: both.

"a cure for white teeth.. ." Uh...make them yellow?

Y'know, I can see the logic behind it although it's not the normal logic I would apply to such constructions. It's kinda like the old phrase "good for what ails you."

In a related story there's the confusion running rampant these days over the verb substitute. To me 'substitute X for Y' means that Y is the default and you are asking to have X instead but I've seen it where it was obvious that it meant that X was the default and you are asking to have Y instead.