My mother, too, considered that Germans were superior to Poles, but I
really don't think that this was particularly addressed at Polish Jews,
but a general German middle-class attitude. Maybe Polish Jews were
disdained because they spoke Yiddisch rather than Hochdeutsch, but my
own family spoke purest Schwaebisch - and I'm sure were in turn looked
down on by the Berlin crowd who spoke Hochdeutsch. Language in those
days was a sure indicator of class - and not only in Germany.
In England, too, class was judged by the way one spoke. At my English
high school girls were given elocution lessons school to eradicate
their 'Brummie' accent, because a "BBC accent" was indispensable for
anyone who wanted respect or a well-paid job (or husband!). Perhaps many
of the early European settlers in America emigrated partly to escape
this class system.
St Albans, UK.