As long as they are fairly new and not the old beat up smelly sweaty kind I don't mind it. I wouldn't ever share boat shoes with anyone though, or any other closed toed shoe that I don't wear socks with.
My office colleagues who are distant cousins and live together share practically everything with each other. Not realizing we notice even the colour of their hairbands. I don't see any wrong in sharing as long as their feet don't smell but i personally don't
My mom, me, my cousin and and my grandmother all use to share shoes. We are all the same foot size lol I also share sneakers with my ex boyfriend and dad. I share with my friend as well, but mainly sandals, because her foot is so much wider than mine. I refuse to share sneakers with friends, but I trust my close family. We all wear an 8 in u. s. mens a 9 in u. s. womens! XD
i don't ever share shoes. one can get athlete's foot if the person you're sharing with has fungal infection. i don't think you're being silly. i don't even share my shoes to my sisters unless it's emergency haha and it's not because i'm disgusted or what cause i'm even the "caregiver" in the family lol. I don't know i'm just hygienic.. :)