scabby bald head
痜 describes a scalp condition: a scabby, bald head. The meaning is narrow and clinical, with no clear broader conceptual center.
痜 combines 疒 (sickness) with 秃 (bald). The exact historical development is uncertain, but it likely expresses a disease causing baldness.
The sickness enclosure 疒 wraps around 秃 (bald). Picture a sickness that makes the head bald and scabby.
For トク, imagine a doctor saying 'Talk about a scabby bald head!' as they examine the patient: talk -> トク.