I agree with everything said so far. This is a tough job to define as many have said; it is very product/process centric. Not only knowing good drafting practices - which are typically interpreted as knowing how to create "lines" in CAD but is really MUCH more - the person must have an understanding of the audience that will be reading the drawing. For example: a machining drawing should be checked by a person with knowledge of what a machinist is "looking" for on a drawing. Same for fabrication, welding, coatings, etc. disciplines.
Certified Sr. GD&T Professional