For the most part, I don't believe orbs are representations of spirits. It's really easy to catch a piece of dust floating through the air on camera, and it looks uspernatural or whatever. There are some pretty interesting examples of coloured orbs and auras and what not but that can be light reflecting off of any coloured object.
Stuff moving around and glasses breaking is a totally different story. I'm by no means a skeptic, but I do like to consider all the possibilities before crying ghost.
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