I agree. Some people (not me as it happens) have better memories than others. If I've been vocal in my love for Judge Rinder and say "Spoiler's out
" then a fair number of people will be spoilt.
I think "Spoiler's out" is fair game because apart from anything else it saves traffic on the DS site. If you don't have the willpower to resist a vague reference to the existence of a spoiler then that's your lookout.
But once it's out then the people who know need to be absolutely squeaky clean about what they say, especially if you've said that you know.
I love the spoiler personally so I tend not to post anything between now and Sunday night, because it's too tricky to work out what's safe.