I was being extremely stupid and accidentally applied a little chain lube to my brake pads? I tried to sand them down a little and cleaned the disc rotor with rubbing alcohol, but the performance is still lower than normal. Is there anything I can do to save them?
Wash them with a toothbrush and about a 1/4 cup of rubbing alcohol for a set of pads. After a few minutes brushing with alcohol, pat them dry with a clean towel. I then use a butane torch to heat them up pretty good. Oil and other contaminates burn away. Generally I stop burning the pads when they stop putting off smoke. Allow them to cool and after, lightly sand the pad area finishing up with another alcohol brushing.
The rotors get cleaned with alcohol, this time using a clean rag. I use a generous amount of alcohol. After all is clean and dry and the pads are reset into the caliper, I complete another "burn in" period with them--up to 10 hard stops from about 15-20mph to zero without locking up the wheel. I would guess I have a 75% success rate restoring acceptable performance doing it this way.
If you're wary of the torch (I'm talking a handheld, refillable, butane torch. It's fairly tame tempeture wise and it works the best), soak the pads in alcohol taking them out to brush them and refreshing the alcohol soak with clean. Soaking the pads for more than 12-24 hours risks softening the resin matrix and then they will be trashed. Follow the soak with a drying period followed by sanding.
I would recommend trying paint thinner with a cloth and old toothbrush. In my opinion, there is hardly a better cleaner for oil/grease based contaminants, and what's better it evaporates instantly leaving no residue of its own.
Acetone or make-up remover is similar, AFAIK.
Obviously, the best idea is to replace, but if for some reason that isn't possible or ideal and you want to try to remove the lube, I doubt there are better cleaners than thinner.
Keep in mind it is inflammable and the fumes aren't healthy , so take precautions and limit exposure.
I wouldn't suggest sanding them as this is basically wearing them down. And yes, if rubbing alcohol didn't work, thinner just might, its usually mineral spirits.