Yea it's very difficult trace if not impossible when done correctly...but you gotta be careful when going BTC -> XMR -> BTC -Allow some time to pass before the final swap back into BTC. Just say a day or two. (the longer the better) -Use different exchanges for each swap and change your VPN server or Tor identity each time -Break up your final swap into multiple chunks, and don't consolidate after ( i.e. Don't go 2.17 BTC -> XMR -> 2.17 BTC ) All this complexity is made worse by high fees going on with BTC, so it is pretty much impractical to do all the time. That's why I just find it much simpler and cheaper to directly spend my XMR where I can Fiat -> XMR -> spend XMR or Large chunk of BTC -> XMR -> spend XMR