A suspiciously high number of backlinks from some related niche websites that aren’t too great in quality. In my opinion, this could be an indicator that the domain name was using a Private Blog Network (PBN) service or their own PBN to boost their authority…this blackhat tactic can work, but it places your domain name at risk and the PBN owner could pull backlinks at any time.
So how do you develop that instinct? NameBio maintains a database of over 500,000 historical domain sales (as of writing this post). They have interesting filtering features by which you can narrow down domains by price range, date sold, keywords and more. Simply sifting through the listings on NameBio long enough will quickly develop your domain appraisal “instinct”.
There’s an important distinction to make here between domain flipping and website flipping. The latter mainly refers to buying and selling full websites. By full websites, I mean websites that actually have content and more often than not have traffic and revenue. When buying and selling websites, the domain name matters less as the main value there is the content, traffic, revenue, history/reputation, sustainability and growth opportunities. The same can’t be said for domain names where you’re just selling “the name” and hence it’s all that really matters.