I see color in many dso's, but you need to be careful. Are you really seeing the color of the neb, or transfering the color of near by stars. In m42 for example, many back ground stars have nebulosity around them. Are you seeing the color of the gas? Or the star? Often times late at night our ep's fog up, this spreads color as well. To judge the color of a dso move the scope around, try to get it away from near by colorful stars. Try looking on different nights and when the object is higher in the sky.