keep cleanliness对么?

clean可作动词也可作形容词
keep clean就可以了

也可以
the user can keep cleanliness of the main body of the slipper when in wearing the latter.

应该常用的是 keep clean 好像从来没有听人说过 keep cleanliness的 更多的是 keep sth clean, eg keep the cup clean

keep意为保持时，通常的结构是:keep+宾语+adj.所以应该是keep+sth+clean,而它作为系动词用时，就是keep+adj.?即keep clean
及物动词 vt. 保持；保存
continue to have or hold,esp.for future use or for a long time
I kept myself warm by wal...