I think there is a ton of evidence that points to Beaton and Crowther scamming Oscar, but what gives me slight pause is Beaton visiting Aurora to feel her out to see if Oscar is just a gold digger and Crowther laying on the whole "Are you sure you want to do this to poor little Maude? She's so innocent, she doesn't deserve to be used" angle so thickly. So I am wondering if maybe this isn't a scam, but a test devised by Maud/Gould to determine if Oscar really is worthy of her and her fortune. I mean, at every turn, Crowther is saying "don't do this," but Oscar just keeps going ahead with it. Maybe Crowther is a Pinkerton?
That would make a lot of the evidence it's a scam red herrings, though, and this doesn't seem to be a show that does red herrings. Scam or test, a lot of work has gone into it.
Who is Maud's "paid companion" Aurora mentioned? That's another monkey wrench because there have also been a few hints that Maud is looking for a beard just like Oscar is.