I watch kids at my house and a strong stomach is an incredible thing to have!
I had one of the younger boys one day and he had a little accident in his pants which ended up smeared all over my bathroom walls.
I don't have that strong of a stomach yet so you can imagine how many times I had to go in,clean for 30 seconds then run outside in freezing cold weather for a bit of fresh air!
You need to be incredibly patient,one of the boys I watch is so hard to understand sometimes that I will ask him to repeat himself 5-6 times before I can actually understand what he's saying.Also with patience,every kid is different some are picky eaters while others will eat ANYTHING.
You have to have a lot of kindness,some kids are overly sensitive and others aren't.The mention of a special blanket or toy and the overly sensitive child could become upset and need that object while other kids don't have security objects.
I think the best quality in a caregiver would have to be adaptibility.You need to be able to work WITH the kids and even sometimes go out of your normal routine in order to accommodate everyone.