Can a private process server trespass if signs say No Trespassing

Most trespassing laws are fuzzy to say the least. Trespassing, basically speaking, is being on private property that is NOT commonly accessible to the general public and being there without permission. Now, this is where it gets fuzzy. Say the defendant lives in a condominium complex with a security door and buzzers that ring into the units. If you stand by the door and wait until you see someone leaving the building and you stop that person and ask their permission to enter, that may be acceptable. Or if someone opens a garage door to an apartment building and you enter the building that way, that too may be acceptable. If you jump over a small locked gate to get to someone's front door, that is NOT acceptable. If there is a "No Trespassing " sign plainly visible and you ignore that sign, that is NOT acceptable. Use your best judgment. Ask yourself if it is worth it. Is there another way? Taken from http://infoguys.com/article.cfm?id=7