"most spies are highly efficient and useful to our governments goals / protecting people from bad things. the hand-full of derps we see in the news are unfortunate but shouldn't be taken as the general state of spying / intelligence work."

Sources?

Because there is this other theory, that the "handful of derps" we see in the media are just the tip of the iceberg, because most failures can and do get shoved easily under the carpet, with a "top secret" stamp.