The hospital received a warning due to the uncleanliness of its operating rooms.

uncleanliness 是由形容词 clean（干净的）加上否定前缀 un-（表示"不"）变成 unclean（不干净的），再加上名词后缀 -ness 构成的名词，表示"不干净的状态"，即"卫生问题"或"不清洁"。