what's the business model of urporn.com?
 

I noticed this porn directory website: urporn.com is buying some junky traffic from popunder networks.
It is having 50M volume according to similarweb, which will cost 5 figures of dollars per month.
I assume it is getting paid for listing websites in its directory. does this worth it? I doubt if there could be a good CTR with these popunder traffic.

Well. Good for them. Bad news for people who work with them.

Similarweb is not the best tool to evaluate a site
 

Similarweb is not the best tool to evaluate a site because of what you just pointed out. SEO traffic is the most valuable, for them, for their clients, and for any site out there. Popunders are just a monetization play. But if people buy them there's for sure some value there. They could also be running ads from an ad network.

and to answer your question
 

And to answer our question, probably a cpc deal as each of the partners captures their site name as a source.

Maybe they do have some organic traffic and these popunders are value-added. I'm sure they are investing a lot on popunders, cuz I see them many times when I try to spy ads for my media buying purpose.