As exposure therapy your homework is to eat your own scabs and tell the therapist how it felt.
Which is more upsetting to you, the act of eating scabs and the revulsion, or the fact that someone will know you ate scabs and the shame/embarrassement?

Next homework is picking your nose, eating your boogers and not rinsing your mouth. Which aspect is worse?

Therapist is proud and pleased about your progress! Next you have to do this on public transport in full view of 10+ strangers, no explanations, no apologetic gestures. What's worse?

If you have had your mouth come into contact with sexual secretions during sexual interactions (with your consent) are you repulsed by the memory of said secretions being in your mouth

Have you put your own sexual secretions in your mouth, on your tongue, tasted them?

Are boogers inherently dirtier/grosser/worse/more repulsive than cum and other such secretions?

Therapist is printing you a t-shirt, which will you wear out as homework. You may not explain the shirt or why you're wearing it.