Pretty much depends on if i know them... If it was a friend of mine, i wouldnt mind. If it was some random person i never met, i would probably be startled, but i might do it anyways, so that i dont seem rude.
Depends... Is it a member of the opposite sex? If so then sure. It's tradition, and a good icebreaker. That having been said I wouldn't be down with french kissing, but a peck on the cheek or lips, why not?
well like pretty much what everyone else said. I was at a Christmas party one year and they put mistletoe up everywhere!! so I would just let people kiss me on the cheek. no one but the hubs gets the lips!