We recently ordered four or five Oreilly Hadoop books from amazon and the printing was horrible. The fonts look terrible and simple things like grey backgrounds are not uniform. The book is still legible but the printing gets distracting at times. I thought it was an indication that Oreilly had lowered there standards.
I have a copy of Programming Robots with ROS in front of me which I was on the verge of sending back to Amazon. The text printing is fuzzy and images have noticeable banding. You can't read text in the screenshots it's so bad. It's like the book was printed in draft mode. I bought it a month ago.
I bought it on sale, but this retails at £40. That's not acceptable. I've bought full colour textbooks with photo quality prints for the same price.
I had a look at a previous purchase, Fluent Python, and it's similar but not as bad. The animal icons (e.g. the ravens with little facts next to them) are still quite poorly printed. I bought that about 6 months ago.
Looking further back in time, I've got some pocket guides to Python and C. It could be a placebo - maybe the paper just feels nicer over time. The printing also looks better, but there aren't any big ink-dense graphics to give a fair comparison:
As an author and publisher using Lightning source, I would argue that our print on demand books are equal to those of any major publisher and better than many I pull off shelves in bricks and mortar dealers.