Itzik_s: “I have even heard those who suffered the most at the hands of their neighbors, namely Polish Chassidim, speaking Polish with construction workers and maids in Boro Park and seemingly enjoying the dialogue.”
The Polish you heard from the Polish Yidden in all likelihood was a very primitive form since very few frum Polish Yidden ever mastered the language because of the rampant Anti-Semitism. Few attended secular schools beyond the early grades and Yiddish was spoken/written exclusively.
Not so for the Hungarian; Czech; German; etc. Jews; for them secular education was mandatory. Many, in fact, never spoke Yiddish.
And the reason that they “seemingly enjoying the dialogue” is because to themselves (inneveinig) the Polish Yidden are saying, “Look peasants, while you and your ancestors stole our properties; tortured and killed us; at the end you Polakim are working for me and cleaning my shmutz”.