Dear Leah,
also a newborn baby may vomit some milk on your t-shirt and if you don't want to risk anything you may want to use a blanket or simply you keep the baby into his pram...

Every piggie is different, but I honestly tell you what my piggies do. Calliope is on my lap and starts watching at me, licking me and being a bit nervous, but DOESN'T wee. If I don't understand her message, she moves backwards until her butt is outside and then she wees (on the sofa).
Calipso does not care of everything and she wees on everybody. But she usually pulls our clothes with her teeth for sending you the clear message. Not always, though.
My former piggie Ugo used to move in round before weeing on us.
Let's say that if I am dressed up or if it is winter and I don't want to risk to change the clothes I prefer cuddling them with a blanket. Now that I stay at home in underwear I don't care (and in fact nothing bad is happening).
About the poo all around, my piggies leave their poo during floor time only in certain corners of the kitchen. The poo does not smell at all and it becomes dry in a short time. They leave also the wee on the floor in certain corners. I don't care... maybe there is some method for teaching them to wee and to poo in a civilised way, but for me their corners are okay.
The hay is flying everywhere... I am always with the broom in hand... but for me it is not a big concern if I have no guests at home...
Piggies boring: also children are boring for a lot of people... I love all the animals but I would not like a dog. We are different and before adopting a pet we need to ask ourself what we are looking for, what we like and what we don't like. I love the cats and I was thinking about a cat; but for thousand good reasons I know that I cannot live in peace with a cat...
Piggies can be very tame and follow you around the house, or can purr to you, or they can do nothing as that and can even be nervous when you stroke them. My Calipso is a bit nervous and during lap time she often turns back and shows you her butt; no purrs; sometimes she bites too... And I can say the same of my second daughter: she did not want to stay in my lap... But I cannot say she was boring for me.
If you are looking for a pet with "no bad surprises" about his personality (and there is nothing wrong in this) remember of talking a lot with the owner of the rescue and of course go only to a rescue; because a breeder has too young piggies whose personality is unknown and the shop has to sell.