Impetigo CAN scar if you scratch and pick at it.
More info: Under normal conditions, if you apply medications as directed, avoid touching the area, and keep the area clean, you should not have to worry about scarring from impetigo.
Scarring Is Rare
Impetigo is a bacterial infection that invades the skin through lesions such as cuts and scrapes. It generally presents as tiny, fluid-filled blisters that may ultimately break open crusting over the infected area. With good hygiene practices such as washing hands regularly, avoiding touching the area, keeping the area clean, and following your physician’s treatment advice, the infection should resolve on its own within a week or two with few complications. 
When Does Scarring Occur?
Permanent scarring and skin damage can occur from obsessively scratching the area, which can not only spread the infection further, but can cause damage to the already susceptible skin where the infection is invading. Scarring from impetigo is rare and easily preventable by practicing good hygiene while the infection is present. 
 “Impetigo.” Medicinenet.com. N.p., n.d. Web. 5 Mar. 2012. www.medicinenet.com/impetigo/page3.htm
 “Impetigo: MedlinePlus Medical Encyclopedia.” National Library of Medicine – National Institutes of Health. N.p., n.d. Web. 5 Mar. 2012. <http://www.nlm.nih.gov/medlineplus/ency/article/000860.htm>