Originally Posted by lespaul23
Make sure there are holes in the bottom lip. Check out the sticky if you havent already read it. Kegs without holes are dangerous for boiling.
Saftey should be first!
And otherwise make sure it is in decent all around shape. Does it sit level and not rock (stability when full of boiling wort). Is it reasonably round? Hold pressure?
Basically you want to make sure it holds what you are brewing and does not cause any safety issues like spilling/blowing up.