People often put their foot it in it and say odd/insensitive things about pregnancy and birth in general, from "you look small/massive" to rambling on about their own horrific birth stories. Initial reactions to homebirths are not exempt from this!
I doubt many people mean to be so inappropriate, but suspect it's more that birth is such an emotionally charged subject that the mum-to-be notices a lot more acutely all comments on the topic. For the person saying it, it was probably just a casual remark and instantly forgotten (not that that makes it ok, but just don't take it to heart).
I had two lovely homebirths and wouldn't change it for the world but it really is some people's worst nightmare. For those people it would be a bad choice as they'd probably be too stressed out. And that is all they can see when you mention that you're thinking of having one - they've had zero reason to research the matter have only their preconceptions to reference.
So do your best to ignore the comments, knowing that you are better educated than them regarding homebirths. Or enjoy correcting them!
As for the mess, the midwives don't leave you swimming in blood and amniotic fluid in hospital, so why would they at home
. Mine brought loads of absorbent sheet things, and the whole lot got swept into bin bags and taken with them. I never even saw the mess.
And if you change your mind at ANY time, even mid-labour, then you can go straight to hospital. Planning a home birth doesn't mean you're obliged to stick to it.