What conditions are good for expired domain
 

That you can easily mold to your porn niche and indexable faster via expireddomains.net

Total of backlinks << I am guessing its best to have 0 backlinks? so you can mold it to your niche?
has alexa ranking? << for faster indexing?

anything else?

tnx

Try to find one with a .edu or .gov linking to it. That's as good as it gets.

It should be expired lol

If you're looking for type-in traffic (ie. the domain is a common key phrase), it does not really matter.

Any hot sites with upcoming domain expirations are usually back ordered before the expiration date.

Ultimately, it's what you put into the domain after you get it, either ad traffic and/or search engine traffic.

:2 cents:

A name that's related to your porn niche.

If a name drops with backlinks, the backlinks are fake. Likewise any traffic, ranking or any other search engine juice.

Don't even waste your time thinking about it, as alluded to in the post above there are professionals who do this for a living. If a name drops the only possible thing of value it has is the name itself, if you like it.

A few tips:

Use https://archive.org/web/

and review ALL history, see anything odd or in Chinese? Move on. It will have been spammed to death

If you do find one that is OK check its backlinks:

https://linksthatrank.com/backlink-blacklist/

You can still, occasionally find some useful domains, but clearly more difficult than 10 years ago.