Other than a strong "EWWWWHHH!" about Cathy H's story(now,the guy who did THAT was GROSS!!), AND about RobinRTrueJoy's(peeing on your HAY? UGH! One big reason I won't have any male DOGS is that I don't want them peeing on everything in sight, LIKE MY HORSES' HAY!!-so I SURE wouldn't want some person peeing on it, either!!)--I have to say that otherwise, the idea doesn't bother me(as others have said, no. 1, NOT no 2!)
Would I want some stranger 'going' in my barn? No, but I am getting older(and those of you who aren't there yet, you will be, and you will know what I mean....), and it is a long walk to my barn back to my house...my stalls have a good sized shavings spot(over dirt, not over the mats), and I have made use of that many times, actually, in the past 27+ years--as has the occasional female friend, while here to go driving-though of course they are PERFECTLY welcome to come to the house to the 'official' bathroom!
I actually imagine the farrier was trying to be thoughtful; farriery is not clean work, and she might have been trying to avoid the possibility of dirtying up your house and bathroom....
Margo