I am trying to check if there are good/valid uses of ["-1" comments.](https://meta.stackexchange.com/questions/333539/cant-post-a-comment-which-contains-1)

I know this is not valid:

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> -1: Bad post.
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But is **this** okay?

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> With all due respect, I don't think this is a very helpful response. There are many vague terms like "more or less established" and "anything earlier than the 15th century is ... written on a scroll". Since Coemgenus is asking for proof of his insightful conjecture, which it appears you cannot prove or disprove, I'm sorry, but I have to give you -1 on that.
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