Collinwood is waaayyyy up on Willow's Hill, so I don't think kids would go trick-or-treating there no matter what. I do imagine, though, that adults in Collinsport are amazed at how many "Kids" in such vastly realistic costumes show up for treats each October 31st.
Myself, I imagine a costume party at Collinwood each Halloween, where everyone dresses up like their ancestors. Only since the ghosts show up, it all gets terribly confusing and Roger is no help at all--he polishes off a couple of decanters of brandy in the first hour or so then starts arguing with Edward, Daniel and Joshua Collins over who is who. Elizabeth keeps telling Carolyn to stop coming as Millicent because she gets too far into character, which puzzles her because she never comes as Millicent, although she herself is always astonished at how gallant Willie manages to behave when he pretends to be Desmond Collins (which puzzles Willie 'cause he's never invited to these windigs).