Plug-in request (Hide user comments)

Hi,

I’ve searched but I haven’t turned up anything so here goes.

Is there any way that a plug-in can be made so that you can hide the comments from one particular user without them knowing?

Example, you have user ‘Troll’ who leaves comment after comment. I can then use this plug-in and to him his comments will still appear but nobody else will see them. He then thinks he’s being ignored and eventually goes away.

I know it’s easy enough to moderate comments and blacklist people but I need to be a bit sneaky here. If anyone can advise on how to do this (even without a plug-in) that would be great.