We have feeders on poles and hanging from the eaves. Nothing we have tried is foolproof, but the best results we have found are using these.
Robot or human?
On the poles, we install these, upside down, around the pole higher up than a squirrel can jump. When the little bastards are on the ground under the feeder they can't see the feeder and tend to not try to climb the pole.
On the hanging feeders we put the oil pan above the feeder. Again the little fuggers can't see the feeder from above and if they do try to shimmy down the wire, they tend to slide off the oil pan.
I have also been known to expend a few rounds of .22LR for the ones that can't take a hint. There's always one!