Linking non-adult on adult pages
 

Hesitating to link a non-adult site on an adult one. How would it effect the ranking for the non-adult site? Does it worth it?

Key problem how could be seen as spam due lack of relevancy between source and destination URL.
Beside, you can see not much adult sites linking to non-adults sites.

There is some relevancy as the non-adult site is about historical tortures and interrogations, with no adult content.
The links would be placed on fetish and bdsm sites.