Below paragraph is from <How Google Test Software>, I do think it‘s a good reference for us. Some rules also can be applied for other document review, for example, on specifications.  

“Reviewing design documents should be done with purpose and not just

be a general breeze through, as though you are reading a newspaper. A good
SET is purposeful during his review. Here are some things we recommend:

• Completeness: Identify parts of the document that are incomplete or
that require special knowledge not generally available on the team, particularly
to new members of the team. Encourage the document’s
author to write more details or link to other documentation that fill in
these gaps.

• Correctness: Look for grammar, spelling, and punctuation mistakes;
this is sloppy work that does not bode well for the code they will write
later. Don’t set a precedent for sloppiness.

• Consistency: Ensure that wording matches diagrams. Ensure that the
document does not contradict claims made in other documents.

• Design: Consider the design proposed by the document. Is it achievable
given the resources available? What infrastructure does it propose
to build upon? (Read the documentation of that infrastructure and
learn its pitfalls.) Does the proposed design make use of that infrastructure
in a supported way? Is the design too complex? Is it possible to
simplify? Is it too simple? What more does the design need to address?

• Interfaces and protocols: Does the document clearly identify the protocols
it will use? Does it completely describe the interfaces and protocols
that the product will expose? Do these interfaces and protocols accomplish
what they are meant to accomplish? Are they standard across
other Google products? Can you encourage the developer to go one
step further and define his protocol buffers? (We discuss more about
protocol buffers later.)

• Testing: How testable is the system or set of systems described by the
document? Are new testing hooks required? If so, ensure those get
added to the documentation. Can the design of the system be tweaked
to make testing easier or use pre-existing test infrastructure? Estimate
what must be done to test the system and work with the developer to
have this information added to the design document.”

Recommend for Reviewing design doc-from How Google Test Software