Old thread but my two cents. If a website looks and feels like somewhere you would stick around and read on a daily basis, fits your niche well and is updated on a regular basis with good content. Then its likely it would be a good acquisition.
Once you have come to the conclusion that the site could be a good fit for your needs you can extend that to research further, using tools such as
SEMRush,
Ahrefs,
Majestic,
Moz OSE. My Personal favourite "guidance metrics" are Moz DA ( Domain authority ) combined with Majestic's Trust-flow, using SEMRush to get an insight into the type of traffic using the site.
Realistically though, a good quality link is something that is relevant and has human value, Authority and trust is a bonus. Diversity is still a key indicator and therefore a diverse profile is a good mixture of high, medium and lower authority backlinks including, providing they are relevant and add value you have nothing to worry about.
Couple of things I generally look to avoid when doing outreach :
- Make sure the site you are trying to gain a link from is NOT an obvious guest post farm.
- If it looks spammy, It generally will be.
- If the site is irrelevant to your topic/website, walk away.
- Doesnt add any value to visitors of the site
- Overtly Obvious link selling
Mike