I have learned to respect ideas, wherever they come from. Often they come from clients. Account executives often have big creative ideas, regardless of what some writers think.
The most dangerous thing that can happen to us, I think, is to permit a feeling to develop that any client is a problem. I have always taken the attitude that no account is a 'problem account' but that all accounts have important problems attached to them - that you can waste more time and burn up more nervous energy by fighting a problem than by taking a positive attitude and solving it. It sure gives you a nice, warm glow when you do.