From Chapter Seven of Deathly Hallows:
"Because Snitches have flesh memories," she said.
"What?" said Harry and Ron together; both considered Hermione's Quidditch knowledge negligible.
"Correct," said Scrimgeour. "A Snitch is not touched by bare skin before it is released, not even by the maker, who wears gloves. It carries an enchantment by which it can identify the first human to lay hands upon it, in case of a disputed capture."
This would seem to be an important fact about Quidditch, and as such I would expect it to be mentioned in the authoritative book on Quidditch — Quidditch Through the Ages by Kennilworthy Whisp. Yet it does not appear to be mentioned there. Other enchantments on the Snitch are mentioned. For instance:
Unlike the Snidget, however, the Snitch had been bewitched to remain within the boundaries of the field.
It is bewitched to evade capture as long as possible.
So why does the very pertinent fact about their flesh memory enchantments not appear in Quidditch Through the Ages?