It may be miniscule, but I took a moment to muse on this minutia.
Sherlock Holmes is so synonymous with "mystery" that he is the mascot of the genre. At my local library the logo for the mystery section is a little image of Mr. Holmes with his memorable hat and pipe, but whoever designed it gave him a mustache! Mr. Holmes did not have a mustache, so maybe they merged him with Dr. Watson, a different detective, or he's in disguise. All the books in this section bear this symbol, marking them as mystery novels.
*I fear the choice of "M" as the dominant letter for alliteration in this bit of silliness is hardly appropriate for this topic since quite a few of the miserable murderers and masterminds of crime have names that begin with "M" (See The Empty House).*