I can't get a weird perfect circle smudge off my LEGO Dimentions disc.

Sorry to hear it. The circle scratch occurs when the console is moved while the disc is in the tray and the console is on (or, in your case, when the console fell). You could try taking the disc to a games store that may have a disc repair service to see
if that helps. Otherwise you would need to purchase a new copy of the game.

Not much of a deep scratch, it was a really weird smudge/mark around the disc.

I plan on going to the store again, see what they can do...

My Conviction disc seems to refuse to work... not one scratch or smudge on it yet my Xbox can't read it. Very annoying!

If you want xbox can repair the xbox but if you are past your first year you will pay the 100 dollar service fee

This is why you need to be sure you aren't moving it or have it on an unstable surface

If you want replacements for those disks you must contact activision as they are the publishers and pay the required fee like 20 bucks

Well when my MW2 disc stopped being read it was a result of my xbox falling over. (I used to have it stand vertically)

Now I have it sit horizontally and I haven't moved it since then. It's just peculiar because I did try to use one of my friends' MW2 discs to see if it worked on my console and it didn't when he said it worked on his. And yet it reads every other one of
my games, but the perfect circle scratches are still apparent.