I know exactly what you guys are talking about - I think it happens to everyone more than enough, and it’s frustrating! There are MANY levels of lucidity, and I think the lowest level is attained when you or a dream character simply say or mention that you’re dreaming; you then “realize” it, but, at a very low level of awareness.
In one of Stephen LaBerge’s books on lucidty, they call this very subject “critical faculty” – meaning, different levels of the ability to realize when something is odd in a dream. The example in the book was this: You’re in a bar, and you see an attractive woman, only, she has FOUR eyes.
These are examples of comments you might make in this situation on these different levels…
Level 1: “There’s something odd about that woman over there…oh, duh…that’s it - she has four eyes!” – and you’d think nothing more of it at level 1.
Level 2: “It’s a shame about that woman over there, she’d be really hot if not for that!” – you realize it more, yet, dismiss it’s impossiblity for something like a broken nose, or acne.
Level 3: “Hey that woman over there is very strange, there must be a freak show in town or something…” – you’ve now realized and pinpointed the exact oddness of the situation, yet, you still subconsciously dismiss it’s impossiblity with false rationalization (a freak show).
Level 4: “Hey wait a minute, look at that woman! Even if there were a freak show in town, having four eyes is impossible! I must be dreaming…” – At this level you fully realize the impossibility of the situation, and become lucid.
I think the best way to avoid having your mind dismiss such odd things like that, is to examine your waking life MUCH more carefully. The more you assess the boundaries of reality while you’re awake, the more you’ll be aware of those boundaries while you’re dreaming…this sort of conditioning will help you to easily point out what is real/not real and what is possible/impossible.
That’s another reason why keeping a dream journal is so important, so you can write down these impossible situations that occur in your dreams, and categorize them - start to become familiar with the impossibilities of your dreams so you can more easily notice them to become lucid in future dreams. Don’t JUST ask yourself, “Am I dreaming?” …ask yourself, then jump in the air, or try to shoot a laser from your finger. If you float, and/or shoot a laser from your finger…well, then you’re definitely dreaming!