Comment by harporoeder

For some context it's worth quoting directly from the published statistics available at (1). Although if this is based on manually tagging something as spam it is probably an understatement.

    Of the 483,127 PRs submitted during Hacktoberfest, only 23,299 (4.82%) were identified as spam, with 19,587 (84.07%) of those being in a repository that the Hacktoberfest team excluded from the competition for not following the shared values and 3,712 (15.93%) being labeled as "invalid" by project maintainers.

1. https://github.com/MattIPv4/hacktoberfest-data