Even single words can be clichés. All words are created equal, but some words have grown more tired than others. That’s true not only of adjectives like unique or azure but even of certain function words. As, for example. Over the years writers have used as to get more information into their sentences:

“No,” he said, as he leaned back in his red leather chair.

That use of as as a coordinating conjunction between two main clauses looks harmless and certainly is not toxic. But there’s something so familiar in it that it reminds readers of commercial magazine stories. There can’t be anything intrinsically wrong with as used in this way, but look for it in opening sentences of admired, anthologized stories, and you’re not likely to find it. The same thing is true for while: