Man !!! I now feel like the only f...kin' guy in the world that has done this !!!! The jury is out and I have been sentenced to death !!! I am now heading to walmart and will buy 12 pairs of freshly minted tidy wideys !!!! Never again will my ass touch day olds.
In Some countries people wear things much longer than needed, because of economic reasons, and supply of water and electricity.
Ie: no washing machine ( You all be surprised, some still wash their clothes in the rivers or buckets), detergent, and it is always the mother doing the wash because the male chauvinist pigs can't do it. Taught early from a young age.
Electricity, and Water in Some homes in third world countries don't have the two mentioned.
Now putting this aside.
Here in Canada if you are never taught some simple common sense, such as this thread, the person will never change, unless they are told or they courageously ask.
Now if the person is cheap that is a different reason, and I know a few.
Underwear, socks ( work socks should be changed at work or home if you work on the shop floor or use work safety shoes) T-shirt/undershirt should be changed daily, unless you go to the gym you can use the old clothes but put new one's when you are done your work out and have showered.
Wash you hair once a week with Dandruff shampoo.
Don't keep underwear longer than 2 years.