So I happened to look back at an old wallet and pulled it up on wallet explorer and it showed a link to a Helix address.
How is it possible to even identify a Helix address unless the address was reused? I was under the impression all Helix addresses were new and were used once and discarded.
Could it be that it was identified because of the static fee taken by Helix/Grams?
Someone smarter than me please educate me.
PS: Also noticed looking back I had a separate transaction that showed taint just looking at blockchain dot info.
It's possible in the same way that market wallets can be identified -- all these sites use so-called "hot wallets" as part of their tumbler, that is, central wallets with a static, fixed address that accumulate the site's coins. I'm bored so I drew you an oversimplified diagram:
http://i.imgur.com/kjTDjwm.jpg
Each box represents a bitcoin wallet address. Left-most boxes are the input addresses (where Helix tells you to send funds), right-most boxes are output addresses (where you tell Helix to send the mixed coins). It's a bit more complicated -- certainly there's more than one hop between the hot wallet and the output addresses -- but once you can identify that central red wallet, you can backtrack to what the input addresses were and thus identify "Helix" wallets (or "Agora" wallets, or "LocalBitcoins" wallets, etc) on the blockchain.