I do not think the takeaway is that Bitcoin Fog works; rather, it is that Bitcoin Fog protects you from the specific strategy used by the authors of the paper.

I do not think the takeaway is that Bitcoin Fog works; rather, it is that Bitcoin Fog protects you from the specific strategy used by the authors of the paper. Another approach might work against Bitcoin Fog. "In the Silk Road investigation, the investigators basically threw up their hands and said "don't bother trying to analyze the transaction graph." So apparently tumblers are effective in practice." Do you have a citation about mixing services specifically thwarting investigators? Maybe the investigators felt that Bitcoin itself was too much to deal with. It would not be the first time a law enforcement agency has pointed to a system with little-to-no security and claimed that they cannot attack it.