u/Dalimey (who appropriately identifies as "LAWFUL STUPID" shared a warning from reddit admins issuing their final warning against making the sub NSFW (despite the fact that the users of the sub are in full support). They promised to reply to it with "roll for persuasion or intimidation" if they got 10k upvotes, and here is the result. Outstanding move.
Admins can see absolutely everything on the site, I assume
Technically they have the ability to do anything there, whether they have dedicated tools to make it easy or worth while is likely a different story. Also heavily depends on functionality of the site.