I did comment and reprint my thoughts here yesterday, but I realize my comment fell into the trap of using "cliché" negatively. While it's taken on a negative connotation, the word itself simply means "familiar, expected," and for the most part creative writers want to skirt the expected.
I've edited my comment below, substituting "negative" and "expected" where I had "cliché":
...I don't think we can take anything out of context and call it negative.
The dilemma in any genre is that a new book has to seem new and yet be familiar enough to be recognized as part of the genre. To me, a convention becomes negative when the author lets convention dictate character. Writers may want to pay homage to their favorites, but characters have to distinguish themselves pretty quickly or die. Spenser was much like Marlowe in his debut, but began to distinguish himself by the second book.
The simplest way a character stands out is by approaching conventional situations in new ways that indicate his/her unique personality. For example, Jim Rockford differed from PIs before him in that he always tried to steer clear of trouble, not invite it.
I think if a writer is really committed to showing a P.I.'s personality, it's easy to avoid the expected. After all, does any person really want to be or act just like another?