Nothing whips up a mental image like the phrase "shampoo commercial hair." A woman—usually white—walks toward the camera with her long, shiny strands rippling in the wind, not a hair out of place.

Hair ads can be so freaking mesmerizing. The models' waves cascade down their backs like waterfalls, curls have enviable bounce, and every shiny strand looks smoother than a baby's bottom. Well, it's ...