Genuine question. And yes, I know that in some cases it might be down to a medical condition. But if it’s not due to medical reasons, why do you do it?
I went into town earlier and came across two people, in separate shops, who were looking around, and constantly huffing and sighing. Then I went into a third shop, and the woman serving me was sighing loudly as she served me.
I think, unless it’s for a medical reason, that it’s actually pretty rude and anti social to walk around doing it!