Facebook Marketplace has a little-known ad option called Cost per Sale that’s supposed to charge sellers only when a boosted listing leads to a sale, but a test by Liz Morton at Value Added Resource found it set up much larger campaigns behind the scenes. Morton boosted a $50 listing at a 20% rate, which Facebook said would cost her no more than $10 if the item sold. But when she opened the ad in Meta’s ad tools, she found a campaign set to run nonstop at $400 a day, and a second test at 30% came back at $600 a day. When Morton asked Meta’s own AI assistant how the boosts were billed, it said they were charged by impressions rather than by sales. Other sellers have posted on Reddit and in Facebook groups that they chose Cost per Sale and were still charged without making a sale.
