I find that my dreaming mind is very crafty and I cannot count on any particular reality check to continue to work over long periods of time. Also, the more sense impressions I have in my dreaming (I tend to have quite a few), the easier it is for my own mind to fake me out. In the end what usually works for me is examining the details of what is going on around me in the dream. Something will eventually jar as not matching my memory of reality as I know it. I just have to be careful to be accessing my memory of waking reality, not the made-up-for-the-dream memory of the self I am in the dream. (Yeah, I have control issues and my subconscious is wrapped around itself like an Escher staircase.)