You're not crazy, you just carried the impressions you were given my the salesmen into the listening session and they influenced your perceptions.

Both optical and copper digital cables carry ones and zeroes. If they are connected well and are used within their limits, then there should be absolutely no difference. A 1 or 0 going in one end of the cable will always be a 1 or 0 on the other end. In other words, a digital cable will either pass a signal or it won't. There's not much room for gray area.