http://walletdvl5avrmoxk2fwsf5b76zkmbkoo3r6kqeesq5hsgnq7xhbciad.onion/non-blockchain-attacks-on-privacy
Sometimes the eavesdropping can be very trivial, for example some forum users publish a bitcoin donation address on their website, forum signature, profile, twitter page, etc where it can be picked up by search engines. In the example of the non-anonymous Chinese newspaper buyer from the introduction, his address being publicly visible on his forum signature was a crucial part of his deanonymization.