A coat rack will turn into a bundle of sticks if you neglect it. When you neglect a coat rack, the weight from the coats will pull all of the arms off, leaving it as a sparse stick.
You go up to the neglected coat rack and try to make things right by cleaning it with soap (そ). But no matter how much you scrub, it won't get clean, the arms won't go back on.
Currently there are no similar looking kanji which exist in the WaniKani learning system