Re: How did guest stars react?
Remember, those sets are just plywood, sheet metal, cheap carpet and paint. What we see as a finished episode, isn't what the actors see on set.
I know that. When I was doing theatre, our set flats were painted muslin stretched over a thin wooden frame. But it's still possible to be impressed by set design, even when you know what's behind the illusion.
Dr. Howard, Dr. Fine, Dr. Howard: For duty and humanity! --Men in Black, 1934