FYI if you want to block avatars at work, you don't have to toggle anything.
In firefox, go to tools / options / content tab / load images automatically (leave checked) and click exceptions. Put an exception for
http://www.tfproject.org/tfp/customavatars/* and all custom avatars loaded to the site will be blocked.
You can also do the exact same by loading the above link with a wildcard (*) at the end in adblock or adblock plus.
In either case the computer with the block will define if you see avatars or not, and when you get home you can see all the NSFW content without having to change anything, and without worry while at work.