If you only want to block some of them--permanently, then you can use Adblock Plus to block specific avatars (or all of them). Other ad/image blockers may work as well. You could also just use some CSS to do it (takes some coding, preferably using Stylish).
I have used Adblock Plus to block many of the most annoying ones. My custom filters list is getting rather large.
The extent of my coding experience was "Hello World" in Visual Basic many years ago. I just don't have the time to learn it, and at 60, I am not as motivated as I used to be.
I installed the SuperStop ad-in and it seems to do what I need. -- IUOE Local 101
