Even on the Airbus the radar isn't that great, I've been in dead smooth conditions with the display showing red and moderate turbulence with it showing green.
The skill in avoidance is knowing what to expect from looking outside, a red return from a CB at FL350 is something to avoid whereas extensive red from nimbostratus at low level isn't much cause for concern. Towering cumulus at higher levels are more of a problem because there is very little water content to reflect back but considerable air currents. These clouds typically place themselves exactly on the airways and aren't seen until you are almost inside.
Weather patterns and formations are often a better guide when looking at the radar than the actual colours. At jet speeds avoiding action needs to be taken early and often a previously decided course of action needs to be revised due to rapid changes in a system.