We play bitey-everything with Brees. She only does it with us right now, but I would probably do it with my father if he encouraged it. She's shy with strangers, so no worries there. With us, she's very gentle in a crazy kind of way. Lots of snapping and gnashing of teeth, funny noises and excitement. No contact unless we initiate it. If I grab her mouth, she'll gum me.
Now, if hubby and I are play-fighting, she thinks nothing of biting me on the butt! I don't know what the difference is to her, but she seems to think a nip is okay then. Brees is insane, but very cute!