How can tell if shampoo and/or soap is washed off completely from your hair/hands?

I have OCD and I always think that there's some soap/shampoo left on my body after I take a shower.


I remember today I washed shampoo off my hair but after a few hours when I touched my hair, it felt really awkward. It also smelled like shampoo.


How can you tell if it's washed off or not.How can tell if shampoo and/or soap is washed off completely from your hair/hands?
well of course they smelled like shampoo! when i am in the shower, after i have rinsed out my hair i ring it out (only works if you have long hair) if more bubbles form then i rinse again. or after you have rinsed it out, comb your hands through your hair and kinda scratch your head (like a hair stylist does when they wash your hair). that way you make sure that nothing is hiding and you got all of you hair rinsed out