To see a scab in your dream symbolises a time of healing. If you are picking at the scab, then it suggests that you are interfering in the healing process. You need to let things be and let things take their natural course. Alternatively, the dream may be a pun for a person who is a scab or someone who is breaking a strike.
The dream may also be a pun on a person who is a scab (someone who is a strikebreaker and works despite striking action).