In my dream last night I tried reality checks, none of them worked so I presumed it wasn't a dream, but now that I have woken up I see that it was a dream, how come my reality checks didn't work?

Also, when you have ludicity in a dream, how clear is it in the dream, does it depend on how long you've been doing it or just if you get lucky, would it be as clear as a RL day?

Thanks