Anyone that the TM went to talk to this family was trying to stop it and turn the attention back to their son..No big surprise that their son got picked...
On the other hand, my son was just standing there being himself, in NO view of the TMs whatsoever. The family in front of us was way more excited than we were (my son gets quiet when he's excited, he's not an obviously excited kid most of the time), and we were all just talking to each other, well back from the TM at the entrance to the building.
It was a HUGE surprise to us when DS was chosen. Now, he does have copper-red hair and was wearing a Gryffindor shirt (cheap one from Old Navy), but again, we weren't in obvious view of the TMs at all.
My son was going to buy a wand anyway, so we knew that money was spent.
Just to add my 2 cents for the people who haven't been...the wand you are offered during the show isn't one of the wands of the characters. It's supposedly based on birth month, though that didn't work *at all* with DS. The one he was offered was one I have heard offered to someone in an entirely different birth month.
DS had already gotten the Harry Potter wand, and didn't want the wand offered after he was chosen for Ollivander's. He did, however, want the experience of buying a wand after Ollivander's. Fortunately for him, DH was willing to buy the wand for himself.
And then DH decided he didn't love that wand AND DS decided he's not Harry Potter after all (note the red hair and the fact that his mom is actually named Molly), so now DH also has Sirius's wand and DS also has Ron's. (of course, that happened on a subsequent trip)
So if your plan is to buy a wand that belonged to a character, that's not what you'll be offered during the Ollivander's show. (but you can buy the wand you want in the proper shop)