It would be kind of helpful in a way I suppose. It depends on the lie, a big lie or a simple white lie to smooth things over. Nightly news might have a segment - is such and such person telling the truth, or not. There are a good many politicians and journalists too that would run into trouble with that segment I'm afraid.
Often times it seems pretty obvious when someone is lying though. At least it seems that way to me. Many for one reason or another want to go along with the lie, either for political/ group support or simply to make money I'm afraid. From books I've read over the years i get the opinion that a portion of what is commonly believed in society is wrong, and many know it to be wrong, or parcially wrong. It is easier to go along with the lie though. Having a policy of truth can bring trouble sometimes for ones career.