I think for this, we need to consider how work subpages are interacted with compared to ones brought up by the Random Page button or others you'd encounter on a standard Wiki Walk.
If you're using the Random button or just clicking links, you don't really have a good idea of what you're getting into outside of the link name from a Walk. The eye is naturally drawn to the page image when it's first opened, and many people won't appreciate having a spoiler plastered in front of them. It's unsolicited information they have no reasonable way of being protected from. Unless it's something like clicking a link to The Dead Guy Did It (random example), but you can still get it via Random.
However, if you actively go digging into work subpages like Tear Jerker, you waive your right to be protected from spoiler content. Logic dictates that a page about sad moments will likely involve things like Character Death, so one cannot claim ignorance that it would contain spoilers. I feel like it would be fair to use a spoiler image for these specific subpages.
Edited by Karxrida on Jan 12th 2023 at 4:39:01 AM
To be honest, I've been spoiled more from people pointing out that a certain image spoils something than I've been from seeing these images, because unless I already know the work I have no basis for who the characters are and what the context is (this is even true with things like Tear Jerker, as it could easily be a tragedy that happens early in the work and I'd still have no reason to think otherwise).
I guess I feel like some people are a bit over-concerned about spoilers at times, I get it for examples but with images they're divorced from context and don't mean anything out of context if you don't already know the context. So I've never really been that concerned over spoiler images, obviously if they can be avoided they probably should be, but I don't know if we need to "crack down".
Working on: Author Appeal | Sandbox | Troper WallIn my experience folks are pretty bad at regulating spoilers (some users even spoiler tag anything from the latest installment even if it's not important) and whether or not something is actually spoiler material is often subjective. One man's "meh this character died in the opening 1/4 of the movie, it's fine" is another man's "saddest death EVER do not spoil this for newcomers." One man's "this happens in the third act, take it down" is "this movie is billed a romance, that the leads will have a big kiss scene cannot be a spoiler".
And of course it's not something IP regulars who are not familiar with the work can weigh in on the same way they can JAFAAC or quality concerns, so threads brought up with only 'spoiler' as an issue tend to stall. I don't care too much for spoilers (I will echo Warjay's "OP: Bob dying is a huge plot twist Me: Who is Bob..." sentiment) so even I am like ¯\_(ツ)_/¯ when there's no alternate suggestion.
That said, I am also amenable to allowing them on moments pages. My preference would ideally be something like "we would prefer not to put a spoiler on a moments page, but only start a thread if you have a suggestion that you can argue to be less of a spoiler".

Wiki policy and indicates that spoilers should not go above the example line, including images. This is a good thing. That being said, this rule has generally been ignored for series-soecific pages with spoilers off - usually moments pages. For regulars, these pages being spoilers off is a given, and ergo, a non-issue, but we can't guarantee a newcomer would would know which pages are spoilers off without clicking on them first. Should we crack down on above-the-line spoilers on such pages, and if not, is there a better way to get the message out to newcomers before they self-spoil?