POD Hardbacks from Lulu Better than Barnes & Noble by FAR!

Here are two images showing the ghosting on the B&N cover. It is easy to see a ghost image of the spine running up the back of the book. On the front it is easy to see where there was an original registration error as well (black stripe).

I am appalled that B&N's printer's quality people let this out the door.

As I had understood it Lulu sends out the book PDF files and other distributors use their own printers when there's a purchase. So the only way to ensure you get Lulu-quality printed books is to buy directly from the Lulu website.

I think that Maggie nailed it.

Consistent quality from one copy of a book to another is a difficulty probably inherent in the nature of POD. In traditional printing, for instance, all copies of a book are run off the same machine at the same time. Once a quality check is made during setup (and print proofs made), every book is going to be identical...and quality checks can be made even during the print run if necessary. In POD, there may be a hundred different books created by the same machine between two copies of yours...even if you order a printed proof there may be any number of other books being printed by the machine in the meantime...and each copy of your book may actually be produced by an entirely different machine. Probably the only way to really avoid this would be to print every copy of a POD book at the same time...but this would run counter to the entire idea of POD, let alone be prohibitively costly to the author.

In traditional printing, for instance, all copies of a book are run off the same machine at the same time.

Not quite right, but close.
It depends upon the capacity each printer has in their own facility and in others.

A printer will produce plates for signatures.
Do not confuse spreads with signatures.

For example an 8 page signature will enable on sheet of paper to have eight pages printed on it.
A second plate for a further 8 pages will then enable those already printed signatures to be fed through another machine, or the same one later to print the reverse sides of those pages.
For a 1,000 books (not pages) the printer will end up with stacks of 1,000 sheets, or more for wastage or larger quantities.
These sheets will be folded, guilotined, cropped and bundled ready for stitching.

It may be expedient for one printer to contract some printing even some operations to produce batches of books. For example covers may be manufacture elsewhere or printed on different presses with different inks.

In these cases there is regular quality control from inspecting a single page to the final ready to sell book.

Print on Demand use digital printers that are the equivalent to giant laser printers where the printing, folding, stitching and binding are part of one continuous process for one book at a time.

There are many advantages to traditional publishing, of course.

But, that being said, it is not necessarily the best course to take for every book. For one thing, the author needs to consider the potential market for their book. Self-publishing is often the very best way to go. The decision also depends a lot on the author's personal motives and goals.

But if one of those goals is to make a profit (as opposed to publishing for the fun of it, say), the author needs to weigh the eventual costs involved in producing a book of equal quality to a traditionally published one. After all, every expense involved will need to come out of their own pockets. One can cut corners in all sorts of ways, of course, but that often means compromising quality. One of the obvious advantages of pursuing a traditional publisher is that the author is not expected to invest a single penny. The publisher absorbs all the costs of publishing the book, from providing professional editing, design and cover art to printing, marketing and distribution. To take just one example from marketing, a publisher can send out dozens of promotional copies of a book to reviewers and others, something that would probably be prohibitively expensive for the DIY author. Additionally, the author is paid an advance against royalties, money that never has to be returned even if the book never sells a single copy (god forbid). 

So, if you think you have a marketable book it is worth not eliminating traditional publishing until after at least making a fair attempt at it.

One thing to not do is eliminate traditional publishing because of a lot of old wive's tales about it. For instance, that publishers will rewrite your book, that you will lose your rights to it, that publishers are only interested in experienced authors, etc....none of which are true.