Does Canelos positive test sully his previous draw additionally?

It's doubtful he just started cheating for this fight. The odds were tighter for this fight already I believe. His team hasn't changed in years either.

It depends on how you think. If you think anyone who tests positive for anything not allowed that they deliberately cheated and have always cheated since they have been a pro then yes it does. If you think he may have eaten bad meat and in all the other fights in which he was tested clean he was clean then no it doesn't. Canelo tested clean for the draw with GGG so I think he probably was clean for that fight. If a boxer is tested numerous times and comes up clean for that fight then I think he probably was clean for that particular fight even if he fails a test a year later. Otherwise what is the point of testing. Nothing that humans do is perfect or foolproof. Errors can be made and tests can be wrong. Innocent boxers can look guilty when they aren't guilty.

Once a cheat always a cheat.