Yes, please put "SPOILERS" in the title of a thread if you're going to post them. As a courtesy to all playgrounders.
That being said, we have discussed this in the past and we decided that posting things after they happen is OK. Even if there are time zone problems. But, as a courtesy to your fellow playgrounders and just simply as adults, we should all do each other the courtesy of spoiler alerts if we have the opportunity to do so. That's just a simple respect thing that I'm sure everyone can appreciate.