Term used either consciously or subconsciously by whites to make themselves feel better. Why would I think this you ask?
Because there is no black trash, yellow trash, or brown trash. Clearly there are a greater amount of whites that are not white trash, in their opinions, although of asians, blacks, and hispanics they must automatically be trash. I'll probably get this definition rejected by a mile because 95% of urban dictionary users are likely white. Also used to represent that whites have no troubles and that they think that they're white trash jokingly.
White Trash definition by Urban Dictionary