In that case I'm not sure if it works. I fully expect the spammers to have the software to deal with similar behavior. In contrast with telemarketers the computers multitask pretty well.

To do that better, what you do is route the password cracking attempts to some honeypot box. By this I mean that you set up common accounts with easily guessed passwords. But all of these lead to some dedicated machine where you're in a pseudo-shell that won't let you do a damned thing.