This topic got me thinking.....I think that if I left Duncan outside a store and someone tried to pet him, he would be fine UNTIL I came OUT of the store which is when he may try to bite the person petting him. There would be no reason for him to bite unless I was there to protect.
Last winter, I remember my roommate telling me that Duncan had gotten out the front door. A girl walking by grabbed his collar and was holding him. When the roomie got close to get him, Duncan turned on the other girl and tried to bite her.