Why Materials Start to Smell Even When They Look Clean

Most people associate unpleasant smells with dirt, poor hygiene, or lack of cleaning. Yet many everyday products develop persistent odours despite being regularly washed, wiped, or disinfected. Clothing that smells as soon as it’s worn. Shoes that retain odour no matter how often they’re cleaned. Plastic products that develop a musty or sour smell over time. Car interiors, gym equipment, reusable packaging, and household items that seem “clean” but never quite smell fresh.