Wait a minute. This whole time was are talking about being covered in guts, but all Michonne has to do it use two dead walkers on a rope and she's safe? This has bothered me for a while now. Sure they tried to give an explanation on it but that's so they can cover a plot hole. Just because those two aren't interested doesn't mean the others can't smell her.
The other walkers couldn't smell Michonne because her "living" scent was overpowered by the 2 chained up walkers "dead" scent. That's always how I percieved it anyway.