I'm now using this plugin to take care of the spam on one WordPress instance of mine:

https://wordpress.org/plugins/stop-spammer-registrations-plugin/

It is not perfect, but it is doing a nice job.

#WordPress #StopSpammers

Anti-Spam: Spam Protection | Block Spam Users, Comments, Forms

Robust security and spam prevention. Leverage our pre-defined allow/block lists. Adjust configurable settings on too many hits, quick responses, etc.

WordPress.org