I think it's generally accepted that unemployment and inflation estimates are based on reliable techniques: what sorts of errors are you thinking of here? I mean, in principle, anything you do could be wrong (you can never reach absolute certainty), but you would always do better by trying to analyse things properly than by giving up.
Edit: I didn't mean surveys in general, I meant the specific cases of unemployment and inflation, which to my mind are the two most prominent examples of people going crazy rejecting well-established facts.
Edit: I didn't mean surveys in general, I meant the specific cases of unemployment and inflation, which to my mind are the two most prominent examples of people going crazy rejecting well-established facts.