Shame
Shame plays a complicated role in compulsive finger picking, dermatillomania (compulsive skin picking), and nail biting. Shame is often felt on both the “front-end” and “back-end” of the habit, so to speak — that is, shame can be both a cause and effect of compulsive picking.
Shame as Cause of Compulsive Picking
Shame at one’s bodily “imperfections” (Body Dysmorphic Disorder) may lead one to pick at them. These imperfections may be as trivial as a tiny strip of dead skin that continually breaks loose from the nail folds, or even a slightly misshapen cuticle that one just has to pick back into shape — or else! 
More complicated than these cases — it may be that some inner, unexplainable shame at oneself may prompt a compulsive finger picker to dig deeper and really injure the skin. This would be a case of true self injury (or Neurotic Excoriation). The causes of this shame can be deep-rooted, and require extensive therapy to effectively treat — treatments such as Cognitive Behavioral Therapy or even prescription of antidepressants have been shown to be successful. The root of the shame needs to be discovered and dealt with in either case.
Shame as Effect of Compulsive Picking
It should be obvious why compulsive pickers are ashamed of what they’re doing to themselves — the results of their picking is unsightly skin damage. The shame one may feel after picking can also be many-sided:
- Shame at the ugly, dead, callused skin that grows over the parts that were picked
- Shame at purposely engaging in self-destructive behavior — behavior that most people would think incomprehensible to do to themsleves
- Shame that they can’t stop themselves — feelings of inadequacy or lack of control (Impulse Control Disorder)
Luckily this “back-end” shame is easier to treat. Once people suffering from compulsive skin picking realize that they may have a disease rooted in real physical or chemical imbalances — even depression — its easier to write off the shameful effects of picking. This leaves the mind free to tackle the habitual behaviors that lead to picking or — in the extreme cases of those who are driven to pick by a deep, inner shame — tackle the deep-seeded life problems that lead them to pick up (pardon the pun) the picking habit.