Another question regarding waistcoats.

I've been looking around online at Target and JC Penney, following recommendations from members here. All the vests I see have a silk (or otherwise shiny fabric) back on them. Would this be appropriate for wearing without a jacket? I was under the impression that those types of vests were only faced on the front because they're designed not to be seen in the back. If wearing a waistcoat with a kilt, wouldn't it be proper to be wearing one that's wool/tweed/whatever all the way around?