'Commonplace' when used as an adjective can be used in a derogatory way, but when used as a noun in relation to aspects of literature there is no derogatory meaning. It is simply used to refer to anything that notedly occurs in numerous pieces of literature. Cliché similarly although it usually refers to a single word or short phrase. Again it can be used in a derogatory way but it doesn't have to be.

Could one use the word 'commonplace' to refer to certain mantras repeated on Mudcat ad nauseam?