Pin­ter­est holds great mar­ket­ing promise ‰ÛÓ 21% of U.S. online adults vis­it it at least month­ly, 81% of the site's users are women, the medi­an user age is 35, and 84% have made an online pur­chase in the past three months ‰ÛÓ but it's not a valu­able social mar­ket­ing chan­nel today, accord­ing to For­rester.