Don't post in them. These are dead on arrival, you know the kind; duplicates, blatant site-whoring, spam threads, terrible topics, ect. Go ahead and PM a mod to get it locked. If no mods are around but no one posts in the thread it will die on its own and you won't have to suffer the affront of looking at it. That is what we call a win-win right there, baby.
And I remember the sticky thread in G&T (I can't find anymore) stating that anyone posting in a spam thread for any reason would be jailed. A mod was de-modded for not enforcing this rule.
There's also another spam thread that was made and deleted instead of locked. I PM'ed the person that replied to the spam thread warning him of the rule and that he should delete his post. So I am unsure if he deleted the post or not, or a mod deleted the post and the thread (instead of locking it).
So is it ok to post in a spam thread without worry of being jailed? Why are some spam threads locked while others are deleted?