Some, in fact probably most of the orbs in pictures, can be explained by dust, light reflection etc etc, but definitely not all.
Most Haunted definitely has a lot to answer for, personally i dont watch it and think its a load of made up rubbish. But just because stuff like that is out there doesn't mean that ghosts aren't real.
I have spoken to many people over the years that have had experiences with deceased relatives appearing to them, and as i said earlier, i have had this experience myself. So are we all hallucinating then, or fooling ourselves because we are grieving, or what other so called rational explanations are the sceptics going to make up to explain these occurrences away?