Mono Mini Contamination?

Hi all,
How do I know if my Mono Mini’s brake pads have become contaminated?
When I first got them fitted, about 2 months ago, I could stop on a sixpence now I can actually turn the wheel when the brake leaver is fully depressed.
I have tried boiling them for 30 minutes but this has had little effect.
I am also rather worried that they seem so hyper-sensitive. I think the contamination may have occurred when I cleaned my bike and squirted some ‘muck-off’ near the wheels.
Thanks