He probably wants to put some gay porn up, and wants to know who clicks it, so he can haze them. Everyone avoid Volpone's spoilers from now on.
Negative. It's not recorded, even in the server logs, let alone the software. I don't even think there's a way to record it.
Well, I'm sorry, but something despicable like that is the only reason I can imagine someone would want the data. If it were idle curiosity about some piddly little thing, it'd be no big deal to ask the individual.
It might be possible put an image on a server you own, then whenever someone clicks the spoiler tag to load the image, it logs their IP. Unless the images are loaded before you click the spoiler tag, which might make some NSFW spoiler tags kinda useless.
afaik, anything behind a spoiler tag is loaded even if you don't click it. So yeah, once you start reading a thread with porn pics in it, you'll get them on your computer, regardless of spoilers clicked. That also means the practice of hiding large images behind spoilers to save bandwidth is useless. You'd be better of using thumbnails.
Actually, it varies by browser as to whether the images are loaded before or after it's clicked. FF and IE load them before. OmniWeb loads them after. I don't remember what Safari or Opera do.