I dunno Ricz, if you've pared your clothing carry down to just the bare essentials, and you don't avail yourself of the bathroom sink facilities often enough and completely disregarding the potential for jock itch &/or monkey butt issues, one would think that
most people with a working sense of smell
juuust might be able to tell that you wore the same undies yesterday, more so if you also wore them the day before, and almost certainly if the day before that too....

pps: