If you picture the actual process behind the expression ‘separating the wheat from the chaff’, it’s easy to see that there is always a great deal more chaff than wheat. You have to pick out the precious wheat, and let the chaff blow away. That’s useful to remember when applying the expression as a metaphor in real life situations. Take this page, for instance.
It’s likely that the great majority of the comments that Posts like this receive will be chaff. Similarly, in the self-publishing world, there is far more chaff published than worthwhile wheat. It’s a shame when the wheat gets lost in the flurry of chaff.
I don’t think there’s a way of providing the facility for comments without letting in all those advertisers who use it to for their own purposes. It would be good if people with genuine comments could use the word ‘Wheat’ in their first sentence! Then I’d read their contribution carefully and not trash or spam it with the chaff.