sounds like the first one has water damage (or from humidity).  is the mark on the 2nd book on the outside of the book pages or on the actual pages?  if it is on the edges then it is postable.

part of me says that if you received one that is good then you at least you got your credits worth BUT if the other two are unpostable then why were they listed in the first place?

if you picked from all 3 books off the persons shelf  then all the books  you received should have been postable to begin with.  if you think you cannot repost them I would at least let the person know what reasons you feel that they should not have been posted.  since you've already marked them received (without a problem) not sure what /or any response you'll get but at least you are making them aware and maybe they'll check their books closer before they post them.

Wrinkled pages are not necessarily water damage. I have bought new books that are wrinkled due to cheap paper and humidity. Unless the pages do not look and feel water damaged (stained and rougher), then I would not assume it is water damage. Not saying the book is or isn't postable, just saying wrinkling edges does not equal water damage. Splits spaces? Does that mean there are areas between the glue spots you can see? Or that the book is cleaving from the spine?

The second book sounds fine to me, but I am confused on the details I think. It is blue, yet you suspect water damage? It sounded to me at first that there is a discard/remainder mark in blue on the bottom of the pages and that they may have used a strong enough marker that is bled a little into the pages. As long as it is not bleeding into the words, I think this is perfectly fine to post to PBS. Or is it like the book sat in something blue and absorbed it? General markings on the edge of the book is fine, just not markings on the pages of text.

Sticky marks from stickers on the covers are acceptable. I use a clorox wipe to gently rub that stuff off.

A lot of books come new with slightly wavy pages.

If it's water damage, you don't have to guess.  I recently spilled water on a brand new book, and dried it immediately.  The damaged pages are so wavy that there is about a 1/4 inch gap between the damaged and undamaged pages.  Also the texture of the paper itself is different.  Like the difference between ironing your cotton blouse and just taking it out of the dryer.  The cover is also visibly damaged.  Water damage is extremely obvious - even without staining (which mine doesn't have).

eta - on request, I can PM a photo of what water damage does look like, since there's no mystery as to whether my book has it.