Prompted because I was quite pleased with my creative and amusing response to the OP of this deleted thread and obviously that response is now lost to posterity.
But it's quite often the case that threads which are started by someone who isn't genuine get worthwhile and valuable responses - sometimes on serious topics people share their own real experiences and those responses deserve not to be lost just because the thread is deleted. Sometimes when the OP is a really obvious troll, witty and creative MNers have some good fun with responses to the absurdity.
I would like to suggest a "Trolls Graveyard" topic where threads that are removed from the main forum can be sent, with settings to stop anyone adding more posts to them but the existing content can still be seen. Obviously not every deleted thread should go there - certainly not anything with hateful or offensive content - just the ones where there is worthwhile content to preserve. I think this would also be helpful for non-troll MNers to be able to browse and see examples of the kinds of threads that have been found to be non-genuine over the years.