I don't think you'll find much without serious research into county records. Those would be scattered everywhere. In the Russell era, financials were published in The Watch Tower. On the private blog for the TruthHistory people there's an analysis of Russellite finances, including the full text of the February 1881 "organizational document" with a scan of the signatures.
That's an invitation only site, but all I did was request access. They seem to grant access on request, giving everyone the benefit of the doubt. I don't know of any analysis of Rutherford era financials, which seem to be more complex. When I was a new Witness (back in the late 40's) the gossip was that the Cadillac cars were the gift of two women living in the South who had money from Coca Cola interest. I wasn't interested enough to find out. At the time, all I thought was, "My how nice of them."
My best guess is that while there is a lot of foolishness tied up in the houses and in the cars, there's little scandal there. Might be, but I doubt it. My impression of the 1916-1942 era is that it was a mean spirited Jerk (Rutherford) against the Flakes (van Amburg would be one) and the Crazies (PSL Johnson would qualify). Probably the real scandals are in their interactions.
The shift from congregationalism to "theocracy" is also troubling. I don't think anyone has really followed that in detail. I believe the real issues with Rutherford rest in his dictatorial grasp on gullible worshipers.