Mark M is correct. As a licensed architect, I know first-hand that -- under the law -- my putting my seal and signature on a drawing is in no way a guarantee that the information on that drawing is correct. The registered design professional's seal and signature by law ONLY attest that the drawing was created either by the registered design professional, or under his or her direct supervision. In my state, architects are NOT allowed to seal anything they did not prepare personally or that they did not directly supervise. Period.
My state's registration laws do include a provision under which professional engineers may seal work they didn't prepare or supervise personally. However, that law includes a provision requiring the engineer to conduct a review of the document before sealing and signing it, and to prepare a written report setting forth the nature of the review he/she conducted. The law does not require that this review report accompany the document(s). We see a LOT of plan stamping in my town, by both architects and engineers. With the engineers, I have started asking for a copy of the report. It's required by law, so they can't object that I'm asking them to do any extra work.
When we know an architect has sold his seal, we can't ask for the report because it's not required (since architects aren't allowed to seal work by others at all), and our town administration has told us we can't report them to the licensing board. So we have to grit our teeth and find other ways to deal with it. A saving grace is that our State Building Inspector recently sent out a notice reminding us that we can accept only "wet" seals or proper digital seals with third-party authentication. Often, "sold" seals are just JPEG images -- so we now reject those, citing the directive from the State Building Inspector. I don't know how much an architect makes each time he/she sells their seal, but our hope is to make it more trouble than it's worth.