Hello,
Frankly speaking, I never met any advertiser (in adult) who was interested in retargeting (except adult webmaster traffic).
Of course, my imagination generates some cases for adult dating and adult cams, but I never seen advertiser interested in it.
What do you think? Do u know any adult-advertiser interested in retargeting?
Exoclick offers retargeting on their campaigns and my ad. manager strongly suggest it to use it.
Maybe if you are offer owner it will be helpful to retarget users.