Can you tell when an adult is wearing a disposable diaper?

No. Adult diapers come in many shapes and sizes. They are designed with tiny beads that turn into gel when they absorb urine. The gel keeps the fluid contained and absorbs odors. Products in a variety of sizes can be worn under most lose clothing without any visual signs.
Incontinent. When he or she is incontinent of urine or feces to protect his/her underwear as well as to save himself/others cleaning work.