If you show too many hands to suggest bluffs, then when you don't show a hand it will imply not bluffing
... showing too many hands probably tends to give too much information.
Showing just the one hand while at a table could have some use, though, as it could confirm a particular image, either as a bluffer or as a solid player, but just the one set of cards, generally, I think, otherwise you give away too much information. It's something to be used only very sparingly, though, and certainly not all the time. Perhaps you sit down at a table, and decide to play a junk hand, and don't get called, you may then want to show those cards, so that the first impression all the players have of you is as a crazy player, so when you then immediately tighten up, you'll possibly get a few more calls when you next play a hand.
Recently in Pot Limit Omaha/8 I've had a number of hands where I've missed a draw or was sure that the other player had made a hand at the river, and folded to their bet, and they've then shown me their hand. In each case, all it's achieved is confirming to me that my read on the player was absolutely right, so I both felt better about the way I played the hand. In that kind of situation my opponent showed his hand with the result of making me feel better, which is the last thing you want, so it just showed how revealing your hand can be a bad thing.