I've found a lot of material on dream interpretation to be pretty crappy. The typical example I give is dreaming of a horseshoe symbolizing good luck. I've never once dreamt of a horseshoe, and have no idea why I would.
I do agree that if there is a Jungian collective consciousness filled with archetypes, then certain symbols could have more than just personal meaning. However, I don't believe in generalities like water means emotions, green means prosperity and things like that.
I've always pretty much known what an important dream meant when I woke up because the feelings associated with the dream were still strongly present. However, I suppose that if someone strongly repressed their emotions for a certain period of time, their subconscious mind might start trying to communicate in code (i.e. symbols) in order to bypass the conscious censor.
Does this make sense, or have I completely misunderstood the point of interpreting dreams in the first place?