I didn't see the show, but let's face it: The TPIR models probably are too busy changing outfits or moving to their next marks to pay attention to details of the host's patter. Hearing what Bob said at the end of the show over the music, applause, and general crowd noise had to be almost impossible, and "Bob Barker saying, 'Goodbye, everybody!'"--Bob's closing during Anitra's tenure--isn't terribly memorable.
On the other hand, you kind of have to be a TPIR geek to know what to ask to ferret out the real Barker's Beauty. Asking her to name the other models on the show at the time might work, but how many non-geeks would know if she was giving the right answer? Non-geeks might think to ask who the announcer was (and know the right answer), but would they think to ask who hosted the nighttime version (if they even were aware of it) or who directed the show (and, again, know if the answers were correct)?