In version 1.3 if you block users you are automatically reporting them to SpamBusted. This way their IP will never bother you again.
In version 1.4 you can add an extra layer of security by checking against Botscout as well. Since version 1.4 uses Joomla transport layer for server-to-server communication, Joomla 2.5 is most recommended.
lIn version 1.9 the plugin only check against Botscout, as Spambusted is no longer available. Also, upon blocking a user the plugin verifies that user against Botscout and lets you know if it's a spammer. Optionally, it allows you to directly delete that user if so.
Had this plugin been checked and these issues rectified, this plugin would have had a perfect rating.
Thank you for your kind review. This was the hope, to help block spam on Joomla sites, without effort for the end user. I am glad you find it helpful.