(1) Blog posts that re-state the mind numbingly obvious as if it were original and insightful.
(2) Blog posts that rehash ideas within a given vein that have already circulated ad-nauseam, without adding significantly to them.
(3) Blog posts that put forward ideas so fluffy, feel-good or ambiguous that it is impossible to disagree with them, but they don't add value either.
Many personal development blogs are mostly a compilation of "wisdom" found on refrigerator magnets. We can all agree for instance, that "it's important to be yourself", except when it's more expedient not to be. This is truism blogging.