While investigating my rm property problem I ran propellor with
PROPELLOR_DEBUG=1 propellor
At the beginning I have the debug informations but not once the ssh connection was initiated on the host.
So I had to log into the host in order to run locally propellor in debug mode.
It seems to me that the PROPELLOR_DEBUG=1 env should be propagate to the host, chroot etc...
Annoyed me a few times too, but not enough to do anything about it.
It might make sense to add a command-line option to enable debug mode, so that propellor can pass it when it runs propellor elsewhere..