I believe that some people do linger, perhaps because they died violently, or because they have unfinished business. Other times, when a person has died peacefully and had nothing left to do, if anyone feels their spirit, it's probably not the person that died. I have two reasons why I believe this:
1. When my grandpa died, my mom and her mom went to the hospital room to say good-bye. My grandpa had just died a few minutes before. Anyway, while they were standing there, my mom said that she FELT my grandpa, and that it seemed like he wanted to say something but couldn't. So she told him, "It's okay, Dad, we know you love us." And immediately the presence was gone. Later, they found out that my grandpa's last words, which only the nurse heard, were "Tell everyone I..." He never got to finish his sentence.
2. My friend Tyler was killed in a car accident almost nine years ago, when we were both eighteen. The last time I spoke to him, I made him promise that when he got back from Wyoming (he went to visit his extended family), he would come visit me in my new apartment. A couple weeks after he died, I was awakened by the sound of someone in the apartment. I tightened my grip on the baseball bat that I always kept beside me while I was sleeping, and opened my eyes just slightly. I couldn't see anyone, but I heard them walking. After they walked the length of my apartment, they stood over me for a few moments, then left. It took awhile, but I went back to sleep. In the morning I thought it was just a dream...until I looked in my ashtray. I always emptied my ashtrays before going to bed, so when I had retired for the night there was just one cigarette butt in there (the one I had smoked right before going to sleep). In the morning, there were two: One was the butt of the cigarette I had smoked the night before. It was a regular Marlboro. The OTHER butt was unmistakably a Marlboro Light, which was the brand that Tyler smoked. I actually did put that ashtray aside, and did not use it again until most of my friends had seen it.
Since that time, I've thought I felt Tyler again and again, but NONE of those experiences gave me the peace that that one did. Instead, they brought me anguish. I don't believe that they were Tyler.
So anyway, sometimes I feel that the "spirits" really are just that. Other times they're not.