On SU there's the Deposit User which is suspended for quite some time. And I also know that it is used for spammers, but how does it work? Does the account of the spammer get 'linked' to Deposit? Do the answers get moved there?
This is a method we are experimenting on Super User.
Users can be suspended, or in some serious cases, deleted completely. This is fine to deal with regular or offending users.
Spam users, the robot kind, are working differently. They will create several new accounts, so suspending doesn't really have an effect here. Deleting is good, but we lose potential information about them.
This is why the current experimentation is to merge them into one account, to keep track of their activity, links posted, etc. Moderators can see that this user currently has six (6) questions and 78 answers, all deleted. So far, mostly fed thanks to your own flags.
It's also a fun game to see how many scalps we slice.