Glad to help.
Yes Blackhole should help to clean things up when it comes to bad bots. Blackhole has over 30K active users and many positive reviews from people who have success with the plugin. So it definitely works.
Just make sure to read through the documentation before installing, and also remember that page caching prevents dynamic plugins like Blackhole from working properly.
I hope this helps, let me know if I can provide any further information.