Its initial concentration was on Sherlock Holmes and related film and television productions, but later its subject matter expanded to include a variety of other genres.

His contact with MPI and their enthusiasm regarding Holmsian fandom led to a decision to change the format from newsletter to full-fledged fanzine (years later, Valley would be contracted by MPI to compose liner notes for their DVD collection of the Granada series, as well as for their releases of the Basil Rathbone Sherlock Holmes film series).

Encouraged by the response, Valley (as editor, with colleague Jessie Lilley as publisher) continued producing issues on a semi-regular basis.

With articles and interviews by respected genre authors, and increased circulation through nationwide distributors, Scarlet Street arguably transcended the fanzine appellation into magazine status, adding color covers and glossier interior content.

Scarlet Street has been criticized by some for having a "gay agenda," due to gay-friendly content and articles that have included discussion of the sexual orientation of genre filmmakers and its possible relationship to their work.