To paint a large section without leaving lap marks, roll the nearly dry roller in different directions along the dry edge, feathering out the paint as you go. After completing the entire length of the wall or ceiling, move to the next section and paint over the feathered edges. For the second coat, apply the paint in the opposite direction. This crisscrossing paint application sharply reduces (if not eliminates) lap marks.
I managed commercial construction projects for many years, have built and remodeled several properties, and never once have I encountered any of these scams. The tone of this article is deeply troubling. The author seems to be saying that ALL painting contractors are inherently dishonest, and that has not been my experience. The underlying advice here is sound: get it all in writing and cover as many contingencies as possible--so pointing out potential pitfalls like coat coverage is helpful. But do that in the spirit of clear communication of expectations, not with the expectation that the person you are hiring will try to cheat you at every turn. Not every contractor takes outrageous advantage of change orders; not every contractor will sneak past necessary preparation and/or repairs. Contractors of all sorts get a bad rap as it is; reinforcing a stereotype with articles written from this point of view just seems unproductive.
