Colon Cleansing- Do I REALLY have pounds of fecal matter, parasites & worms in my colon?

I know that you've seen the infomercials that talk about this stuff... that there are " toxins and parasites" filling up the large intestines (colon) of hundreds of people and that we need to use their ($$$) stuff to flush out the impurities. Is there any truth to this? Would a standard enema be enough to flush out the colon? What about the flushing aid called Golightly that one has to drink before a colonoscopy... wouldn't that work? Or, does this scheme just fit into the snake oil category? I would ask here that people from a medical background please respond to my question- Thanks!!!