We find that hot water is the best method.
Run it as hot as possible, and hold the
electrodes underneath. You can also soak
them for a couple of minutes in the hot water
in a glass, then follow with a hot rinse.
10-20 paste is completely water soluble,
and hot water makes it thin out, melt,
and run off the surfaces. Then dry them
completely. They can be ready to re-use
in 15 minutes to 1/2 hour.
I do not recommend using alcohol, as it attacks
the gold plating, leading to eventual wear-off. If
you stick with hot water, electrodes will last
for months and years.
We also do not find it necessary to scrub them.
Again, this wears on the surface, and is unnecessary.