I used to have 7 pairs of clean underwear. One for Monday, one for Tuesday, one for Wednesday, and when I got to Sunday I’d put on the last clean pair and wash the rest.
But I got to thinking, what if something happened on Sunday and I wasn’t able to do the wash, I would be out of clean underwear.
So I wised up. I now have 12 pairs of underwear. One for January, one for February, one for March…
To be sure, ick-factor notwithstanding, if the OP’s hypothetical “couple” are actually, y’know, a couple, then they’ve probably already shared all the E. coli and other germs they’ve got with each other. Wearing undies for a second day still has a day’s worth of ick factor, but I don’t really see a hygiene problem with swapping drawers. But… as numerous posts have asked: Why?
But, . . . washing your underwear in the hotel room sink – Now there’s ick factor!
I don’t wet my toothbrush by rubbing it on the surface of the sink. I hold it under the faucet and wet it with fresh water. So why would I care if underwear has touched the inside the sink?
My perception is that the cleaning staff cleaned the sink before I got there, I clean my underwear with soap, and I rinse out the sink with soap. How would I survive if I were that worried about a tiny chance of a trace of my own ick?
To the OP, you don’t need to bring any underwear. Just look for used ones in the trash. That way you can do your grocery and clothes shopping at the same time!
I don’t know if it was that brand but I bought some undies that were supposed to work like this and the results were unpleasant. They did clean up ok but a day wearing synthetic fibers was much stinkier than cotton or wool.