Why does my brake pads sound like they're rubbing or grinding even after the brake pads were replaced the rotors were turned and they were greased?

Some cheap pads will squeal. You may need to change to an OEM type pad. It can also be you did not apply a anti-squeal high temperature grease to the back of the pads where they contact the caliber. Teflon coated shims are another option. Be sure and also check the slide pins to make sure they are not rusted. Apply a slight amount of high temp grease to these pins or replace if they are rusted.