it's legal to pose as someone else to serve papers. On the ebay boards, a member is pursuing to catch the criminal that sold her a fake LV, so the investigator who is going to serve the criminal with papers, is going to pose as a UPS man.
I've been served before. They had to track me down because I was living with a boyfriend at the time, but my address was still my parents, and they had no idea where the house was I was living in. They followed my car to the mall when I was spotted, and they served me in the parking lot.