About the zombies not noticing Michonne. Let's think about that for a minute.
How do they notice humans, by smell and movement (or sound) Rick was able to walk around them when he covered himself in zombie guts. they did not care for him.
As far as Michonne, she was walking like them. she was walking slowly and not moving her arms or anything. so movement wise, they wouldn't have noticed her. (She was also not making any noise while walking)
As far as smell, I guess the one mistake they did was not have her pets closer to her. That is the only thing I see wrong about it. she should have had the zombies walking right next to her or as close as possible. Perhaps Michonne having each zombie to her side. I see that as being a problem because they were too far from her.
But I didn't have any problems buying what Michonne did (besides the smell) because like I said Rick already did it before.
Besides as soon as she killed that girl zombie with the braids they ALL noticed her right away. it only took for her to move her arms around and the pets stopped working
Yeah I never understood the mechanics on how that works. I guess if you pull a Shaun of the Dead they won't notice, but they can smell you which should would give you away. But if you have an entourage of amputee zambeez and smell like Irish Spring soap you're A-OK?