Bug#181073: acknowledged by developer (Doesn't make sense)
D> apt-cache policy is not supposed to show the status of an installed package.
D> apt-cache show does that.
No it doesn't. apt-cache show doesn't even tell you if a package is
installed or not.
dpkg does though:
$ dpkg -l ibmonitor
iF ibmonitor 1.0.1-4 Interactive Bandwidth Monitor
I.e. F for Failed installation. I was just thinking it would be
appropriate for apt-cache policy to note that something is wrong in
its otherwise beaming reports about a package's status.