Well, I'll share a dream I had once, where the dream imposters did succeed and nearly had me for good.
I wasn't feeling well and took a nap on the couch, and soon was in a deep sleep... I dreamed that my mother and her mother (my grandmother) had appeared in my dining room and woke me up from my nap on the couch. I knew they were both deceased and asked them why I was able to see them... "what's happened?" They both proceeded to tell me that I had passed away in my sleep and that my father "got lost", because he was in an accident and had also passed away and that I needed to find him and bring him back to the house. They urged me to hurry because time was of the utmost importance. I somehow instinctively knew that in his confused state, in "this realm", thoughts could create entire new worlds in which to get lost in, and I needed to hurry so that he didn't "wander into another world". I quickly ran out of the house, hopped into my car and began searching for him... instantly, the streets and roads began changing, yet somehow they were familiar to my dreaming self. And I finally did manage to find my father.... but then I somehow instantaneously found myself in a college dorm room with a bunch of kids I didn't know. I tried to ask them what had happened and where my father was, but they were speaking in some incomprehensible Dr. Seuss backwards english... I knew it was english, but it was all mixed-up and frustrated the hell out of me because I couldn't communicate with them. So I left the room and wandered the building looking for a way out, which I finally found. Right outside of the building, there was a stone bench upon which this HUUUGE dog (probably a wolf, but I didn't think of him as such) was sitting there, and when he saw me, he immediately jumped down and ran to me, all happy and licking me and wagging his tail. From that point on, the dog was "my buddy", my only friend in that crazy place, it seemed. I began exploring the rest of the area outside of the building and saw that there were a lot of people gathering down by this dock. There was a large lake next to the campus, and all of a sudden, the clouds literally opened up and *people* started falling from the sky and into the lake. The people on shore were helping them out of the water and everyone seemed to know what was going on. I finally managed to get a straight english answer out of someone as to what was going on, and they told me that these were the "scheduled" people who were "crossing over" to this world... as in the people from earth who had died. I didn't believe any of it, and I began yelling at the top of my lungs, "THIS IS A DREAM!! I WANT TO WAKE UP NOW!! THIS IS NOT REAL!! WAKE UP!! WAKE UP!! WAKE UP!!!" I kept on going like that for some time screaming until my throat was hoarse, reciting my name and address and willing myself however I knew to leave that crazy place and wake up on the couch!... Nada... Nothing worked. I plopped mysef on a bench, and "my" doggie jumped up on it too, layed his head on my lap and gave me an unmistakably consoling look. I was just in mid-sentence of saying, "Well, I guess it's just you and me now, buddy... I don't want to believe that I really died, but...."
And then.... holy blessed interventions.... the phone began ringing back in the "real world", and the sound of it was just enough to jolt me back into "reality". I jumped up off the couch as though I'd broken some sort of invisible restraints, my heart was pounding out of my chest... and when I answered the phone, I was soooooo thankful to the caller! I didn't realize it until later, but I must have sounded like a lunatic... but I didn't care. I'd been tricked and had almost been made to believe that I was dead... and I truly think that if I would have finished that sentence in the "dream", "they" would have had me trapped there, and I probably would have "died" here. *shiver*
The entire thing was completely lucid, as far as dreams go... but then again, I don't think that was just a lucid "dream", because I couldn't wake myself up, even though I knew I had to be in a dream. Scary stuff, and I really hope that never happens again. I've become extremely suspicious when encountering deceased loved ones during dreams now.
"Sometimes I wonder whether the world is being run by smart people who are putting us on, or by imbeciles who really mean it." ~ Mark Twain