Aged domains attract investors because they promise a head start: existing authority, indexed history and links that would take years to earn. The promise is real for a minority of names and an expensive illusion for the rest. The difference is due diligence, and most of it can be done in under an hour.
Start with the history
Look at what the domain used to be, not just what it is called. Archived snapshots show every incarnation of the site. A name that was a legitimate business for a decade, then expired, is very different from one that was rotated through several unrelated topics or hosted content you would not want associated with your brand. Any period of spam, gambling, pharmaceutical or adult use is, for me, a disqualifier.
Judge the links by their source
Link counts are the least useful metric in the listing. Open the actual referring pages. Links from real publications, institutions, forums and businesses in the domain's original niche are what you are paying for. Links from expired-domain networks, comment spam or unrelated foreign-language sites are not assets; they are liabilities that may already have been discounted or penalised.
Check whether the strongest links still exist and still point to pages that could reasonably be rebuilt. A link to a specific product page that no longer makes sense adds little unless you recreate something equivalent.
Look for penalty signals
A domain with meaningful links but zero indexed pages and no ranking history in the past year deserves suspicion. Sudden drops in referring domains, or a spike of links followed by a collapse, often mark a manipulation attempt. None of these are conclusive alone, but together they should lower the price you are willing to pay, sharply.
Decide the plan before the bid
The most important question is not what the domain was worth but what you will do with it. A name only justifies its price if you can describe the site it will become, the audience it will serve and the revenue model that will pay for the acquisition. If that description takes more than a few sentences, the domain is probably not the opportunity it appears to be.
Pricing the risk
I set a ceiling based on the rebuild value, then reduce it for every unresolved question in the checks above. Walking away from most auctions is normal. The economics of aged domains work because the occasional clean, relevant, honestly linked name is worth many times its cost, and that is only true if you have not spent your capital on the ones that were not.