A simple rule to learn and remember.  It won't solve any problems, but it will make it easier to plan your actions (and reactions):

When a woman gets her hair done, however she feels about it when she comes home will be the exact opposite of how she feels about it a week later. 

If she comes home crying, take comfort in the knowledge that within a week she'll decide she loves it after all.

But if she comes home smiling and happy, try to schedule a a business trip or in-patient hospital surgery for a week later, so you can avoid the hysterics when she decides how much she hates it.