We don't have a lot of foot traffic, but some of my fosters seem nonplussed by the visitors and others to the hiding routine.
If I have a scared one, I physically carry them out to greet the visitors, get a quick pet, and take them back to their safe area before real terror sets in.
How else will they get used to it? I always make it the least traumatic for them and try to end it on a good note.

BTW, my little scared, fat girl is coming around socially. She will go on a long transport to her forever home. I think she will adjust quicker this second time around, having had so much interaction here in foster.