Domains are different from Websites. Domains is all about the name itself, Websites is about the profit, you can easly get scammed with a website but not with a domain. I believe its safe to buy domains on Flippa. I never bought any, but sold some. Everything went fine. Just a tip: many domains listed on Flippa are also listed in another marketplaces like godaddy, namejet and sedo. Before making a purchase take a look on this places as the prices can be diferent.