JakiChan,

If you're a Firefox user, there's an add-on you can install that will do what you want - swing over to http://www.tycamtech.com/extensions/firefox/ffvb/ and install it.

I just gave it a try, and it completely hides threads once you've ignored a user. If you copy/paste the thread address, you can see the thread with the ignored user's posts excised.