I would image that simmering below the surface for all those years was a lot of resentment and apathy from the general population of the Warsaw Pact members. The Soviets had to forcefully put down popular uprisings in Hungary and Czechoslovakia, which would have also led to a lot of the populace wanting an end to perceived Soviet domination. You also had the natural long lasting hatred between the Poles and Russians that has went on for centuries. Poles resented the fact that their proud nation was now a Soviet satellite state. The alliance was basically held together by the implied threat of Soviet tanks rumbling through the streets to restore order.
There was that old saying in Eastern Europe about the Soviets : They are our brothers, not our friends. Because you can choose your friends, not your brothers.
How would the armies of the half hearted 'allies' of the Soviet Union fare in a WW3 conventional type war? Would there be mass defections of Polish and or Hungarian forces? The Soviets did allocate a division to shadow a Warsaw Pact unit in case of war. Even if there was no defections, there would be a lot of apathy and malaise among the Warsaw Pact nations.