Is the gunk removed by exfoliation really dirt?

Generally speaking, the residue produced during exfoliation is not necessarily all dirt. The detailed explanation is as follows:

The stratum corneum is the outermost layer of the skin, composed mainly of tightly packed dead keratinocytes, forming a strong protective barrier that helps prevent the invasion of external harmful substances while maintaining skin hydration. In normal physiological metabolism, keratinocytes gradually age and naturally shed—a natural process of skin renewal. When performing exfoliation, the material removed is not entirely composed of these aged keratinocytes. Some of it indeed consists of dead surface skin cells and impurities; removing these can improve skin smoothness and cleanliness. However, ingredients in exfoliating products—such as abrasives and surfactants—can also mix with sebum and sweat on the skin's surface, forming the residue that is rubbed off. This portion is not entirely "dirt" originating from the skin itself.

If you wish to exfoliate, it is recommended to visit a reputable medical facility and undergo chemical peeling (such as glycolic acid peel) under the guidance of a qualified dermatologist. This procedure involves applying a high-concentration glycolic acid solution to the skin’s surface to promote shedding of the aged stratum corneum and accelerate skin cell turnover and repair, thereby achieving exfoliation and improving skin texture. The typical cost for a glycolic acid peel ranges from 1,000 to 5,000 RMB per session. Symptoms usually begin to improve within 1–2 days after treatment, although side effects such as peeling and stinging may occur.