When I was at Andover, I overheard two people talking. One was a tour guide and the other was a prospective students.
The prospective student: I am so nervous for the interview
tour guide: No, don’t worry you’ll do great, you just have to be yourself and don’t lie. The interview is more like a convo.
Prospective student: Ok thanks.
Tour guide: I’m sure you’ll do great! These tours are not like graded or evaluated so don’t worry.
Yeah. That’s all I heard when I was walking by.
@Sroo, great advice for BS tours & interviews and life in general!
It seems that schools conduct tours in different ways at different times. DS toured two of the schools you mentioned, and both of his tours were individual. One school paired him with a guide who shared his specific interests, and the guide at the other school was randomly selected for a more “organic” experience (we were told). Both tours were instructive and fun! I have no doubt that this was because we were relatively late in the season and the schools had extra capacity when we visited.
At many schools, it’s apparently a thing for other kids to prank the tour guide by wishing him/her a “Happy Birthday!” A tour guide at one of the above schools told us that it’s not unknown for parents to send elaborate gifts and even large-scale balloon presentations, presumably in an effort to curry favour! 
My favorite tradition! Some of my friends even have prepped monologues for it because they know it’ll happen.
It’s not really bullying or anything; people only do it to their good friends.
We had this on just about every tour. My son has been warned by his teammate about this. When someone wished our guide at one of the schools “happy birthday” my son asked the guide, “so when is your real birthday”, he said, “it’s hard to believe but it really IS today.” Not sure if that was really the case or not but it was pretty funny.
Yes @confusedaboutFA, it was all very good-natured, and DS’s tour guide was fabulous!
I saw the same at two schools I toured. The tour student was greeted with “happy birthday” everywhere. I asked the interviewer later, he said the birthday was probably close enough–like that week. What are the chances a tour happens in the week of their birthday, 1/52 ?