I think there is a chance it is true, and until people witness it for themself they will more than likely say it's complete cr*p.
I believe people who we know and/or love when they die are still around so to speak, they are in heaven, but seem to keep a certain presence around us on a daily basis. The bond even after death between two people stays, and the more the connection say a husband and wife/ lovers is stronger than say someone you met once or twice. They seem to be there with you, maybe they are just noisy lol ....no I think it's lovely.
You might be thinking oooo freak well I have never seen anything and just believe in the presence of the ones you love.
If there was an angry presence, then it might be a liitle more 'active' and will show itself. I think the people we love don't show themselves because they think it would be more detrimental and upseting than us just thinking their around in 'spirit'