The danger is seeing a pattern where their isn't one.

Once we have decided that a pattern exists we tend to accept the evidence that supports the pattern and ignore the evidence that challenges the pattern.

So, instead of a rough generalisation we end up with complicated stereotypes that cast all .............. as ...................

Migrant workers do generally suffer from racism (Robert Miles, Racism and Migrant Labour around 1987)eg. Chinese cockle pickers and other agricultural workers suffer, Doctors, nurses and entertainers much less so.