I do reality checks in waking life to remind myself to be aware and question my reality, instead of just floating along through life like it's a non-lucid dream. That way (in my reasoning at least) I'm more likely to notice something odd, or notice that the feeling is different inside a dream and become lucid. I haven't (yet) become lucid because of a reality check, and I've never had to confirm it's a dream with one -- once I question it, I seem to just "know" whether it's a dream or not unless my subconscious throws up some weird explanation and I brush it off. However, doing a reality check in a dream does seem to make my awareness and clarity increase, possibly from the excitement of seeing the check succeed. I'm hoping that I'll be able to randomly do a reality check in a dream out of habit as others have stated, as a way to become lucid instead of just by feeling or seeing something odd.