I'll 2nd (3rd, 4th) the motion on Bar Keepers Friend. Works great (use with water, and rinse thoroughly). It's especially effective if the hone is really neglected and clogged heavily, as the oxalic acid makes all the difference in dissolving the embedded steel particles. They'd be next to impossible to simply scrub out, if really clogged with swarf.
If the hone isn't too dirty, some Comet/Ajax & water works well, especially if used in conjunction with a Scotch-Brite pad (I use this with the BKF also).
I one is motivated enough to clean the hone after each sharpening session, some dish soap & water will handle that pretty well. Scrub with a Scotch-Brite, sponge, toothbrush, etc.
I also noticed recently, you can use some Simichrome/Flitz polishing paste to scrub most swarf out of ceramic hones. Just rubbed it on with my fingertip, and then washed it off with some dish soap & water.