If I had more than just the most basic arithmetic skills, I might be able to whip up a Good Will Hunting-level equation so that one could calculate—preferably beforehand—whether driving some particularly annoying washboard road is a good idea.
There are many variables. How badly do you want to get there? Do you know from personal experience that you'll enjoy he destination, or are you going only by someone's recommendation? How well do you trust that person's opinions? Does the person like you, or is he prone to playing mean tricks? How bad is the washboard? How much of it is there? What damage might it cause to your vehicle and/or its contents? How's your spine? Would you care whether your brain was shaken to pudding?