Madison Avenue thinks a tasty approach will give new life to Welch's grape juice.

Welch's is taking out full-page print ads in People magazine this month that give readers a chance to sample its grape juice by licking the ad. The front of the advertisement shows a huge bottle of the juice, while the back has a strip that peels up and off, with text that reads: "For a TASTY fact, remove & LICK."

Marketers...