Thanks
aerobod - your explanation makes sense to me, at last! The clue being that the uneven cleaning doesn't actually occur while applying (moderate) braking, but with constant dragging of pads against the inner rotor's area...
Will do the bedding procedure, but - since it involves some "smearing in" between the rotor and pad materials - I'll only do it after my rotors are (almost) free from any remnants of iron oxide
Piotr