A lot of 'rouge' ssh traffic comes from hacked machines. If you contact the abuse department of a provider, they may get in touch with the owner of the machine to let them know that their box has been compromised.
Yes I know that, but I'm not convinced that the cost/benefit really makes sense for complaining. Back in my more idealistic days I did report a lot of abuse. But it's so rare for the recipient to actually do anything about it, and the volume of scans so high, it's just not worth my time.
