How to detect that a domain is easy to replace?

The "ease of replace" is kind of domain name metric that impacts evaluating of the domain name value.
E.g. a company may select other similar domains rather than purchasing given one. But there may be such domains that have minimum possible alternatives thus are more valuable.

I assume seasoned domainers may forecast "ease of replace" before purchasing or appraisal of a domain.
But I found it tricky so looking forward for some insights how to detect possible alternatives of a given domain…

How to detect that a domain is easy to replace?