I've been hearing lately that certain colors should have certain _other_ colors as their primer. For example, I've heard a grey-tinted primer makes blue finish paint more vibrant. Is that just the paint companies trying to sell more product? I'm repainting a bedroom with sound, clean walls and wasn't going to prime but if I decide to prime, and if the colored primers make a different, I might as well use them. Any thoughts or experience to share?
Chris