I am the father of 3. One boy and two girls. Boy came first and it was no big deal. Cleanup was a cinch as I knew all the parts and where to be. Newborn poop isn't bad. It's a few weeks before things start stinking and then you wonder how something some adorable can smell so bad.
With the girls, at least the first one, it took me a LONG time to get comfortable with the process. Completely opposite of the boy, with the girl, I had no idea where to go, where you'd find poop and how to properly "excavate" the area. The running joke amongst my buddies was that my relationship with that area previously was far different and it DOES take some getting use to. After a bit, it became business as usual.
Never quite gagged me out with any of them. However, there have been some brutal experiences that had me quesitoning what the hell they ate.
Two horrible things of note:
1) When the kids have gotten "rhinovirus" (sure that's not quite it). They'd have the runs AND vomit. And it would all smell the same. You'd literally hear one of them blow in their sleep and before you got into their room, you'd smell that distinctive smell. To this day, THAT will get me cramping up.
2) The use of diaper geenies. You'd pack that thing full of diapers. And if you'd empty them every week, they'd sit there and ferment. And no matter how you tried to take them out of the diaper geenie, a poof of warm poo air would escape and blast you right in the face. Nothing better than stale poo air.