I wouldn't consider my website to be a well-ranked website on Google, but yet here I am with this Bing issue. I believe you're right: Bing allows spam-links to taint the reputation of a URL until they decide that the URL — the victim that has nothing to do with the spam-links — should go. Incredibly unfair and nonsensical for a search engine.
Through Bing Webmaster Tools, I can see pages being crawled, but not indexed. Bing has the sitemap and all the URLs. The robots.txt allows all crawlers. Even if there was an issue there, it would be on their end, and they should be the one fixing it. The result is the same: a mysterious disappearance from their SERPs. And no way or clue on how to fix it.