Just got done working on the car.

The rear left wheel's left brake pad had worn all the way down to the metal, and it was ugly. The other side was worn down to just past the groove side.

I took the wheel off and put new pads on both sides, and then took it for a test spin. It works perfectly, despite the deep grooves that cover 60-70% of the radius of the disc rotor. The brakes feel fine, but I get that rotor resurfaced this week. But, all in all, the operation was a success.