I've taken my beater to car shows before -- ask Jeffy he'll tell ya what he really thinks of it's looks. Though under the hood my game is won.
Nothing wrong with taking a stock car to a show -- talk about mod you'd want to do and at an all focus event I bet you might even find yourself with some options to go home with or to. Sometimes just polishing it up and cleaning it up is worth taking and talking about. You don't have to be the main attraction, or even an attraction at all.