>>42675519>Do the jannies actually check the links? You'd be surprise.
>As per the contents of the remaining book. There is an unwritten rule here on 4chan, if you wish to post NSFW on a SFW board, often times posting a link under spoilers is good enough, as long as the image itself isn't completely disgusting, and the current atmosphere of the moderation of the board. You see this in many Drawthreads. It is unwritten because at least the poster is trying to serve common courtesy by linking it externally in a way that doesn't violate the board rules.
If the artist/poster links a fetishy image, and the rest of the gallery is straight up porn, then the link in question isn't really under fire, (nor would direct links to the porn) because of the unspoken unwritten rule of common courtesy.
There is an exception to this; if the poster/artist deliberately is trying to advertise their own page/channel/etc by baiting NSFW's (Like posting FA/DA/Aryion/Patreon etc) on a regular basis, then its considered advertising
This again depends on the moderation atmosphere whether or not this is deleted or not; if it were to be deleted, its not because of the content link but rather the attitude of the linker.
tl;dr. It's cool, just don't abuse it.
*Fair warning*: I'm not actually a staff member, just an observer of since 2008.