If we wake up and remember a dream, and then attempt to record it or describe it,
we usually realise that the dream is nonsensical. It will contain events
and perceptions and places which are in some way derived from our normal
waking experience and memories, yet they are put together incorrectly.
At the same time, if the dream was non-lucid, then it probably made sense to us when we were experiencing it. The bizarreness is therefore only experienced later, with the wisdom and insightfulness of our waking state.
Dreams are not very coherent, but it may be accurate to say that they are sufficiently coherent given the reduced mental faculties of their audience.