Often people will use expensive products on the skin and honestly don’t cleanse. If you don’t have clean clear skin the product will find it hard to penetrate the skin. Cleansing and sunblock are the most important steps to a facial routine.
Often I will get a facial client (who wants to buy a serum or moisturiser) to go home and use their own cleanser between the next facial if they are not in the practice of cleansing the skin. It is probably the longest step in a routkne, they need to prove that it is not a waste of their money buying products that won’t work.