Having worked in Yeshiva High Schools for a while, I've seen this unusual practice of students automatically standing up for any visitor to a classroom - including custodial staff, parents who are visiting etc. This is done even in the middle of shiur, such that it causes some disruption to the learning process.
One issue that comes to mind is the question of showing deference to a talmid in the presence of the rav, (ב"ב קיט).
Another consideration - if students are trained to stand up for anyone, doesn't that diminish the notion of Kavod - since if everyone is honored, no one is honored.
Thoughts?
Thanks,
Yitz
