Removal requests in Search Console for 404 error

Selected answers from the Dumb SEO Questions Facebook & G+ community.

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  Patty Mantaloons: Only one. The old XML sitemap makes no sense to me though.
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  Bill Hartzer: Are there any links to them from other sites ?
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  Webado C Webada: URL removal requests only work for urls that are currently indexed. 404 error reports are typically based on cached content. Does that xml file respond with a proper 404 or 410 at least? I`d have 301 redirected it to the current active xml sitemap url, or better, reused the same file name for the current xml sitemap. This way old cached copies won`t keep haunting you.
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  Steve Gerencser: In the grand scheme of things, I don`t put a lot of effort into this sort of cleanup. If there were thousands of pages, or even hundreds, I might worry about it. But when it is these sorts of random things I make one or two attempts, declare that Google sucks, and move on.
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  Patty Mantaloons: So here`s a comment someone made on a forum today. Is the following true?: "... Marking a 404 error as Fixed tells Google that the page should exist and to try again. It is a never ending loop. You tell Google the page should exist, Google tries again, the 404 remains as it should, and you tell Google the page should exist, Google tries again... and so on, and so on. Only Mark a 404 as Fixed when a page should exist and you want Google to find it."
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  Steve Wiideman: Try to replicate with a third party crawler first, perhaps Botify, DeepCrawl, or OnPage. If the Linked From are all internal pages try accessing them with HTTPwatch turned on to double-check the response code or to validate a single redirect. If all is well, mark as fixed one more time for luck and then pull a peer in to troubleshoot if it happens again.