Boston Tea Party: Costume Optional?

In an 1884 article reprint of an earlier newspaper story about the Boston Tea Party, an editor at The Bay State Monthly remarked, "This account of the Boston Tea-Party … taken, verbatim, from The Boston Evening Post, Monday, December 20, 1773 … adds another link in the chain of evidence to prove that the Patriots were disguised as Indians." Why did the editor feel there needed to be a "chain of evidence" about that point? Was there ever any doubt that the Patriots were disguised as Indians? What really happened at the Boston Tea Party? What sources can help us find out?