I haven't done this at a large scale(most of my bigger Flippa sales have been web services I built myself) but I routinely see sites on Flippa with decent traff

I haven't done this at a large scale(most of my bigger Flippa sales have been web services I built myself) but I routinely see sites on Flippa with decent traffic and authority that are very poorly monetized. If you can optimize the advertising to appeal to your target market, maybe line up some direct media buys or premium ad networks, you can do very well without worrying about SEO or increasing traffic.