For some reason, Japanese washing machines build up a sludge of some kind, out of sight, on the underside of the drum, and at some point it builds up enough that it starts randomly leaving small deposits on your clothes like speckles of mud. This sort of defeats the purpose of washing them.
洗濯機の汚れはなかなか掃除やりにくいですが、この商品 で簡単にピカピカになりました。400円だけで、かなり良いバリューです。
It's particularly maddening because the washer we have has special cleaning features meant to avoid this, but they apparently do not work.
I thought that I could take the thing apart myself to clean it, but it turns out that to get the drum out you need a special tool not available to the general public (a “hammerless flange nut turner”), so at one point I had to have a service come in and clean it ($200!).
Six months later the speckles were back, and not wanting to make a habit of paying $400/year in maintenance on the washer, I gave the $4 cleaner shown at right a try. It worked fantastically.
You fill the washer with hot water, pour this stuff in and agitate for a few minutes, then let it sit overnight. All the sludge ends up floating in the water and it's really gross... but after draining and running a couple of non-load loads, our speckles are gone. At least for now.
If you live in Japan with a Japanese washer, this stuff is recommended.