It sounds like it was just a normal DC playing tricks.
But the concept of DG is itself controversial. It has not been proved that everyone can find a dream character that is consistently sentient, and can supply useful information.

As to why our subconscious play tricks with us... Well LD is a bit interfering into the normal dream mechanism of the mind, as most people don't LD naturally, so it can be expected that some absurd tricks happen. You can't expect our subconscious to simply "play along" when we meddle with it's inner workings, and reliably supply us with useful and correct information.