Us members of Southern Mediterranean decent, have an issue with what is referred to as "Nose Grease".
The LCD, straight from the box, is prone to this. I have to clean the LCD after a couple shots.
I use the Invisible Shield on my 40D. This tough layer of clear plastic film like problem handles this very well. I can shoot all day if necessary.
More importantly LCD clarity is great and does prevent LCD nicks that you see on many used cameras.
For $19.95, how can you loose.
Canon 5D Mark III (x2), BG-E11 Grips, Canon Lenses 16-35 f/4 L IS, 17-40 f/4 L, 24-70 f/4 L IS, 70-200 f/2.8 L IS II, 70-200 f/4 L IS, 70-200 f/4 L IS Version II, 100-400 f/4.5-5.6 L IS Version II, TS-E 24 f/3.5 L II, 100 f/2.8 L Macro IS, 10-22 f3.5-4.5, 17-55 f/2.8 L IS, 85 f/1.8, Canon 1.4 Extender III, 5 Canon 600 EX-RT, 2 Canon ST-E3 Transmitters, Canon PRO-300 Printer