The stereotype is right, except for the "rich" part. And it's mostly applied to "porteños", the inhabitants of Buenos Aires. Natives from provinces can get a "pass" in short time.
I wonder, do people from Paraguay "get" the accent from the different provinces? I mean it is pretty easy for us Argentines to differentiate a porteño from a cordobes and even someone from the northern provinces (specially if they use slang) with a short conversation
Granted, whenever I had any sort of conversation with someone from Paraguay I had trouble to differentiate their language from someone from the Argentine northeast unless they started using some Guarani words (and that is still not that useful given it is also spoken in the Corrientes province)
Some accents are very distinct, such as the Cordobese one you mention. Others, not so much (e.g., people from Rosario), they come off as "Argentine" and that's it.
