I'm trying to get a lower bound on spam PRs filed. If you sort by oldest (instead of by "relevance" as the parent commenter did) and do a spot check, you'll see that a lot of the PR's are legitimate: https://github.com/search?o=asc&q=amazing+project+created%3A...

Certainly, restricting to the title misses plenty of PRs. But his search provides 252 PRs, and I'd estimate that easily <100 of them are spam.