On the one hand, there is a clear distinction between question and answers, and (especially if there are a number of comments) the first answer may be off-screen without scrolling. On the other hand, I like how this answer gives a hint, keeping the full solution in a spoiler. On the third hand (what, you don't have one?) I don't think we really want half the answers on this site to be nothing but one big spoiler tag.

Overall, I think we should not use spoiler tags for answers. If you don't want the answer spoiled, don't go that far down the page. However, since hints would be nice for many brain-teasers here, I think we should add hints to the question, in spoiler tags. Like so

Hint 1:

To make a spoiler block, prefix it with >!.

Hint 2:

Not all markup is hidden by the spoilers. Check the preview before posting.

On the one hand, there is a clear distinction between question and answers, and (especially if there are a number of comments) the first answer may be off-screen without scrolling. On the other hand, I like how this answer gives a hint, keeping the full solution in a spoiler. On the third hand (what, you don't have one?) I don't think we really want half the answers on this site to be nothing but one big spoiler tag.

Overall, I think we should not use spoiler tags for answers. If you don't want the answer spoiled, don't go that far down the page. However, since hints would be nice for many brain-teasers here, I think we should add hints to the question, in spoiler tags. Like so

Hint 1:

To make a spoiler block, prefix it with >!.

Hint 2:

Not all markup is hidden by the spoilers. Check the preview before posting.