The best thing for cleaning pads is our microfiber cleaner:
What we do:
Fill my sink with water as hot as my hands can handle.
Add 1-2 oz of Micro Restore.
Add pads to the water.
Massage pads to clean them thoroughly.
Rise and lay out to dry.
For really baked-on stuff, use some APC or Dawn as a pre-treat.
This works fantastic for foam, wool, or microfiber pads.