Let's look at the scriptures.
Jude: 8: Likewise also these filthy dreamers defile the flesh, despise dominion, and speak evil of dignities.
2 Peter 2: 10: But chiefly them that walk after the flesh in the lust of uncleanness, and despise government. Presumptuous are they, selfwilled, they are not afraid to speak evil of dignities.
Many sermons and lessons I have heard take up these verses and substituted "dignitaries" for "dignities". That seems to fit in with the idea that they despise dominion and government. (But who are they?)
But two verses after both verses, the speaking evil is brought up again:
..., speak evil of the things that they understand not ...
And the grammar of the verses in question in no way indicates that the speaking evil of dignities is equated with despising authority. Concurrent with, but not equated with.
And if we consider the meaning of the word "dignities", there is a broader meaning here. Government and authority include some dignity, but dignity is by no means limited to government and authority (or even dignitaries).
I think these verses should only be used to preach against criticism of government or authority by those who wish to call their own understanding of both government and authority into question.