A chain of eight laundromats in the south San Francisco Bay Area has been told that its laundry ad showing dirty undies isn’t clean enough for the silver screen. The proposed ad pictures an overflowing clothes hamper and soiled undies on the floor, accompanied by the words: “Are you buying underwear to avoid your laundromat?” Promoters of Oasis Laundries Inc. wanted to advertise on 16 area movie screens operated by AMC theaters, a subsidiary of National Cinema Network of Kansas City, Mo. The movie ad was to complement a billboard campaign that has used the same picture for three months. Oasis was told that the men’s undershorts on the floor was the problem, and the ad could run if the shorts were deleted. Oasis management found that “absolutely ridiculous” since millions had already seen the picture on billboards. A spokesman for National Cinema in Kansas City said the ad did not adhere to its G-rating, family fare policy.