After Nazi brainwashing they see people as crud and kill humans
like scuzzy animals.
It was beaten into their empty heads that people who antagonize
against Americans must be crud, dirty shit, rubbish, just for the
birds. The outcome of this is the bestial perception of a Nazi slaughterer
and it becomes easy and funny to slaughter such as the 'jewish filthy
pigs' in former times
Same methods - Same reason - The Pest has a name