I’ve seen many photographers, on my photo expeditions and elsewhere, constantly looking at their DLSRs’ LCD screens to check if their just-captured image looks right. This reflexive action, which has become a habit to some, wastes considerable time, and potentially results in the loss of the ‘decisive moment’ we all hope for. The fleeting smile, the momentary look, the brief twinkle in the eye, can be all gone while you have your head down looking at the LCD figuring out if the histogram or “who-knows-what” is correct or not. Of course, the question is why don't the DSLR manufacturers gives us an option to turn the display off? Maybe some do, but Canon doesn't.
I know that many of the war photographers and conflict photojournalists actually put black tape (you know, the tape used by electricians) over their cameras LCD screens to stop them from looking while photographing (they do that for safety reasons as well). Another more elegant solution is what is peddled by Delkin Devices as Pop-Up Shades. These come in different models to fit most DSLRs, and provide protection to the screens and double as glare guards. I’m not sure I’d like them, so if I catch myself peering at my screen too many times, I might try the electrician tape solution first....but others may prefer the pop-ups.
Delkin Pop-Up Shades.