You might want to ask Larry Hall, the ISSCA Car Show Steward for some clarification here. I went through the ISSCA judges certification course at I2K2 and had my car judged there with the Colgen Bra and Mirror Covers ON. I show it that way because I like the way it looks and feel the bra enhances the car. I do the same at Super Chevy.
Larry's instruction to the judges was that if an option is in place (like a bra, floor mats or fuel rail covers) you judge the option. In other words, you look for the option to be clean, wear free, properly installed, etc... There was no instruction to assume any option was hiding damage or dirt.
So it's personal preference.