It’s not as formal as their employee vetting process, but people have published photos of themselves being turned away. I know I read about at least one and I think also a second group this happened to at PZ Myers’ blog Pharyngula. There was at least one other small group I read about this happening to in a similar science blog, but it’s all fuzzy now.
Keep in mind, these people were not quietly standing in line and blending in with the natives. They were speaking openly amongst themselves (and not whispering) and I remember one group even had buttons they’d made for the occasion.
