The antonyms for the word "ultraclean" would be words indicating conditions opposite to clean and spotless such as dirty, filthy, grimy, polluted, contaminated, tainted, impure, unhygienic, foul, messy, smudged, stained, etc. These antonyms indicate the presence of impurities, dirt, dust, and stains on a surface, object, or living space, making it unclean and unsanitary. The antonyms of ultraclean are often used to describe areas that require cleaning, such as kitchens, bathrooms, and industrial spaces. Maintaining a clean and hygienic living space is essential for good health and well-being, and regular cleaning helps to prevent the spread of diseases and infections.