Is 'white trash' an offensive term?

I'm not white but whenever one of my whites friends say it I kinda think to myself 'you say it so casually? Is it not an offensive term?' Yes I've said it before in a general context but I'd never refer to someone as white trash, especially not to their face where as my white friends seem to have no problem saying to people. Is it an offensive term? Or is it not as bad as I seem to think