you can check each plug with a volt meter checking continuity from the tip to the center of the electrode, a visual will tell you if the electrode tip is worn, black lines along the ceramic parts or deep below the electrode tip will tell you if its also not firing right, but at this point, replacing them all is in your better interest. you got them out you might as well replace them.
Or invite Steel over and have him check them for you while you sit in the jeep doing the cranking part.

I am sure he would be most happy to check them out for you...