This election made me just not care about approval ratings or polls. They are totally just meaningless statistics for me now. Trump showed they don't matter
Actually they were pretty accurate in '16, nationally and stade-wide. All RB states were within the margin of error except for WI, while Trump has slightly ahead in NV.
To the OP's question: Internals are often biased or under/overpoll certain voter groups to get a better results for the candidates themselves to gain momentum ("see, we're winning in the polls").
