This image from the FAIL blog nicely illustrates the distinction between tanning to have darker skin and being born with darker skin– when is dark skin acceptable/desirable and when isn’t it? Presumably, this advertisement comes from somewhere near the U.S./Mexico border, and although it is probably meant to be funny, the point it makes is real. A white person (the blond pictured in the ad) can tan until they’re dark– which is acceptable and often highly desirable (which still surprises me in the day and age of skin cancer). But, getting a very dark tan, or being born with darker skin in the first place, means that near the border you might be “held by security” (although with the blond on the billboard, I doubt that mistake would be made).
And here are some images of desirable tans from tanning company websites: