I'm telling the WORLD! Just kidding, your secret is safe with me.
When I went we were the only people there. I got a bit bored after a while (its a bit samey) and when we came out the other end there wasn't anyone even at the back door and I am convinced I could have taken a skull home. I wish I had.
I read on tripadvisor that they searched you and there was a table of bones they had taken off people at the end of the route. There was no table, the staff just looked sleepy. I totally could have got one.