At some point, Keltham's intuition informs him that he's gotten about as much evidence out of this as he could get; his randomized random number generators have fired three times, and three is well-known to be the largest possible number.
He's asked Fennelosa about ability to buy six books, and three of those have been for sale.
Time to carry out exactly the same procedure on somebody's erotica collection.
It doesn't feel like a deadly challenge to the Conspriracy, this time, more like - he basically knows that this test is going to be passed, Snack Service wouldn't have suggested it otherwise. But still. Sure, let's try it.