Before making a purchase on Facebook Marketplace, researching the item's history can help you avoid scams. Checking completed listings on eBay or Craigslist's 'sold' section can provide valuable information about the item's market value, authenticity, and any potential red flags. For example, if you're buying a used phone, looking up its model number on eBay can tell you if it was previously damaged or had issues with the seller. Similarly, checking for sold listings on Craigslist can give you an idea of how much similar items have sold for in your area. By taking this extra step, you can make more informed decisions and avoid buying counterfeit or problematic items from scammers.