I managed to get some oil on my XT pads but saved them by…
– stick them in a caliper that you know is working
– ride with the brake on to get them reallllly hot
– poor water on them
– ride with them on again – the water etc creates a paste
– repeat 2/3 times and they were fine
If that doesn’t work get a £7 set from superstar, they work a treat.