$ apt-cache show policy
N: Unable to locate package policy
E: No packages found
What do you mean, APT, you can't locate my package policy? Did I screw up /etc/apt/preferences somehow?
How strange, I can't even find another occurrence of this error message on the interwebs...
Oh, you can't find a package named "policy". Erm, yeah, I don't know where I got the idea that this was a valid command either. Sorry, that one's on me.