Why does Holden refer to Stradlater as a secret slob?

Answer 1

Holden Caulfield refers to Ward Stradlater is a secret slob because Stradlater appears to be neat on the outside (well groomed, etc.), but the methods he takes to achieve the look aren't very hygienic, such as using a dirty razor to shave with. Ackley, on the other hand, is an obvious slob

Answer 2

Holden refers to Stradlater as a secret slob because Stradlater appears clean and neat on the surface, but Holden knows that he is messy and disorganized in private. This contrast between his public image and private habits is what leads Holden to call him a secret slob.

Answer 3

Stradlater appears to be a neat person, but really is not. One example of this would be his razor; it is rusty and has never been cleaned.