I received a paperback book today I requested.

The dilemma is I do not believe the book is going to be repostable for me.  While the book itself appears to be in very good shape, on all three sides of the page edges (when the book is closed) are what appear to be stains like motor oil?  Or some other liquid- coffee?  Not sure what.

I want to mark the book received, but I am concerned that maybe I am being a bit "nitpicky" for an otherwise good condition book?

I have lost credits in the past because I received books where sections fall out (one book it was about 1/4 of the pages in a clump) and the book is not repostable.

The book arrived in a bubble-wrap mailer and I looked inside.  There is no stains or wet anything inside indicating this occurred during shipping. 

I don't see where the dilemna is.   Mark the book RWP and PM the sender and ask for your credit back.   You may or may not get the credit but by all means ask.   State the problem, ask the credit back from the sender and hope for the best.   If they refuse - let the sender know that you will mark it unresolveed until you get the credit.

Liquid stains on the edges of the book had to have bled into the pages of the book too.  This is definitely RWAP so mark it as such and request your credit back, like Cozi said.  Liquid stains are not okay.