Taking
something at face value means to not look any deeper into what is being
said. If the listener tries to
read into it, the wrong conclusion will be reached.
No ulterior motive. Just read/hear what is presented and do not read into it.
Take this at face value, but you look really hot today. Where did you get that
shirt? (If the listener didn't take it at face value, he/she might wonder if the speaker is interested, romantically or otherwise)
Take this at face value, but you had mentioned the cost of getting a nose job yesterday and how much you wanted one. I
saw the prices. They're really not as bad as you
thought. (If the face value clause were not
said, the listener might be offended. It could be construed the speaker is implying the listener should get a nose job because it looks bad or whatever)