'03 EC 300, rear brake weirdness & sanity check

[brider]

My rear brake has never worked (properly) since I got the bike, no obvious signs of leakage anywhere and the pedal SEEMED like it was firm enough, but there was NO braking action. Swapped in a new MC & reservoir, and verified that the caliper is not frozen and is not leaking, and moves freely on it's sliders. Tons of pad material. Bled the new MC with a vacuum bleeder, and I believe I purged all the air; the pedal feels exactly like it did with the original MC, but there is just NO braking action. Sure, if it's on the crate and I spin the wheel I can lock it with pedal pressure, but riding around the yard I can stomp on it and there's nothing. So:

1. I didn't bleed it properly, and the previous MC & system wasn't bled properly, either (doubt this, doesn't feel like air in the system)

2. The pads themselves are useless blocks and are either contaminated or somehow just not grabbing the disc. Sprayed everything with brake cleaner.

Which is it? Seems obvious, but I should replace the pads so I KNOW their condition, I just have never had a set of pads, front or rear, just NOT work. Do I need to remove the caliper (& wheel) to change the pads?

Opinions?