During the first episode of Season 3, I noticed the group is now very cavalier about taking down walkers:
This is a staunch contrast from the first season when they covered themselves in walker parts to get through Atlanta. I don't have that scene handy but, in my mind, it seems like they were very cautious in how they covered themselves (e.g. seemed like they were wearing HAZMAT suits).
I understand that, as time passes, the characters learn more Walker do's and don'ts; but I was under the impression if Walker blood got in their system, they would turn.
Is this true or have I imagined this rule?