This question has been asked several times in the past six years that I'm aware of.
A Canon DSLR does not need another protective cover.
It already has one. Anything added merely protects the protective cover that's already there. (birth control pills AND a condom?). 
When I first saw this topic six years ago, a replacement plastic LCD cover was costing in the neighourhood of ten dollars (likely a bit more now). They are stuck on with self-adhesive, can be pried off (gently) and the new one stuck back on.
Finally, let me say this: it's usually Nikoners that use them. You wanna look like them? 
Glenn
EDIT: Just saw Hogloff's post - he's right of course.