Final answer:
Linens should be changed when they are wet, damp, soiled, or very wrinkled to maintain hygiene and comfort.
Step-by-step explanation:
The question pertains to standards or practices concerning the changing of linens. Typically, linens should be changed when they become wet, damp, soiled, or very wrinkled. Being wet or soiled poses a hygiene risk, and excessive wrinkling can be uncomfortable and unsightly, which could mean the linens are no longer providing a clean and pleasant sleeping environment. A related fact is that you use an iron to remove wrinkles from your clothes, which suggests that if linens are very wrinkled, this detracts from their appearance and function, hence they should be changed. It is essential to maintain clean and tidy beddings for health and comfort purposes.