JStor seems to be a big offender of sending bad DOIs to Google Scholar, which then sends them on to me. Google Scholar is full of bad DOIs from JStor. DOIs which don’t resolve, but have a JStor prefix.
When I find them, I’ve been clicking the button CrossRef provides to report them to the publisher. It’s not clear if JStor actually is interested in fixing this or not. They usually email me back with the full citation. So I’ve started putting in the comments field “I am a systems librarian, just alerting you to the issue, don’t need the citation.”
If they told me “We’re aware of the problem, and am working to fix it, please stop reporting,” I would.
But in the meantime, when I run into them in my testing, click the ‘report to publisher’ button I will! And it is not hard to run into them in testing, they’re everywhere.
Since Google Scholar usually only gives me author, title, and DOI — when the DOI doesn’t actually resolve to metadata at CrossRef, it’s pretty a pretty useless citation.