Most dreams can be quite wierd, like the one you described. That is why many of the lucid dreaming techniques work well! One important concept of lucid dreaming is "reality checks", which means to compare the surroundings in order to find something "wierd" or "different" so that you can find out wether or not you are in a dream

Wierd dreams happen ocassionally to most people without doing drugs. Nothing unnatural about that

My experience is that most dreams I have are more or less wierd. Perhaps the dream descriptions you have read here are from lucid dreams? In that case, it isn't impossible that they seem quite ordinary. Being lucid combined with control over the dream will allow you to alter the dream, which perhaps is what the authors had done in this case.