To be honest, from the giants like Sony, Warner, Universal Studios etc.....to the actors/actresses and sports clubs etc...
They have far bigger fish to fry with regards to copyright infringements than contacting wgt with a DMCA notice in order to get them to remove a certain member's 100x100 px profile logo. They turn a blind eye to it as there's no harm being caused....and it's not worth the time/money or the hassle to them.....to deal with such a trivial matter. There's literally millions of sites throughout every country in the world using such avataars.
Remembering that there are numerous studios who re-sell on images to be used as avataars for this sole purpose....so where does one start to check.....it's timeless....that's if in fact the actual image being used has had it's copyright breached lol.
Copyright infringement's a multi billion dollar business......and you'll find the copyright abuse depts are up to their necks for decades to come, trying to close down torrent sharing sites, warez sites,pirated movie sites, music sharing sites, da de da de da.....for these are the types of culprits in breach of 3rd party copyright laws causing the loss of revenue to the multitude of household names.
The copyright of the images we see on here may be owned per say either by the Film Studio....or the photographer who took it or even the actor/actress themselves, so it's the actual image owner who is the one who would needs to be contacted.....this in itself would be a timely / almost impossible task.
Many images we see in every day life and think hold copyright values are actually in the public domain....i.e they've been released to the public for any use other than making money from the released image.
However, let's take YankeeJim as an example....
Try calling the Yankees stadium and ask to speak to whoever owns the sole rights to the logo and can you speak to the man in charge of it all. Then explain to them that you're calling them because someone is using a 100x100px lowest resolution image of their logo as a personal avataar in a golfing forum.
If you're lucky to even get through to the correct department at Yankee Stadium, they'd most likely ask you to call back after you'd sobered up.
I can only image what Trey Parker would tell you to do ROFL.
Custom South Parks....a great place to make your SP Image.....and their privacy/copyright policy FAQ states...
"Can I use my cartoon for ____, put it in my blog / myspace / etc?
You created your cartoon, you can put it wherever you want. We would appreciate it if you linked to us and gave us credit, but post away."
TBE