There is nothing new to say. We all need to accept that. Every plot, every character, every phrase we use can be found somewhere else if we know where to look. George Carlin used to play around with concocting sentences no one had ever used before, like "Hand me that piano," and I guess there are exceptions of that type, but they're hardly useful in actually writing a story.
The problem, then, is that sometimes we reach too far in trying to come up with a new way of expressing something: a new analogy, a new descriptive phrase. Sometimes it sounds fresh; other times it's too much.
Most readers will go a long way with the author on this; others want it kept real. Dave Barry makes fun of song lyrics in DAVE BARRY'S BOOK OF BAD SONGS, because lyricists often go way overboard while trying to make a rhyme, meter, or thought work out as needed. He has a lot of valid criticisms; I'd never considered the silliness of phrases like "Guilty feet have got no rhythm." (Stilll like the song.)
The book I just finished is excellent plotwise, voicewise, pacewise, but every once in a while I felt the author's stretch for a new descriptive phrase. It was as if it was just out of his reach, and he went too far to grab it. Of course, writers notice such things, being always on the lookout themselves for fresh phrasing. Maybe the average reader slides right over it, even appreciates it.
I guess what I'm saying is that there's a fine line between sounding fresh and sounding frivolous. Ya gadda be watchin' yourself all the time.