I’ve honestly never heard this, never done it or had anyone do it to me? I would always change the sheets before a guest stayed but wouldn’t necessarily change it immediately after?? It’s not like I change my sheets daily!
It’s a very common thing people do. It’s obviously not the same for your own house as you’re going to be the one sleeping in your bed every night so why change it daily?
similarly the guests are not going to strip the bed every night during their stay, when it’s only them getting back into the bed. Guests are stripping the bed when they’re leaving your house, because they know the next person who will use the guest bed won’t be them, so are assuming you’ll wash it at some point before using it again.
Sometimes people do it to hide something they find embarrassing. I was staying at a male friends house once with him & his wife and kids who were staying in serviced apartments as they’d recently moved to the area . My period started and I have a really heavy period flow. I was mortified when I leaked all over the bed through the sheets and into the mattress protector!
Thankfully it was a serviced apartment so when the daily housekeeping called round in the morning and asked if we wanted any beds changing , even though I was leaving the next day, I was like yup! I got a new mattress protector and sheets phew.
But if I’d had to leave that day with the bloody sheets on the bed. I’d definitely have stripped the bed and told his wife too, so she was well warned.
And yeah I know we’re not kids but I prefer not to discuss my periods with platonic male friends lol ( not embarrassed talking about it with romantic male partners though)