I was looking at the second-hand books at St. Vincent De Paul thrift store this afternoon and I noticed a black NWT. It had the regular flex cover like the ones they used to put out in the 1980s. However, I noticed that instead of the sewn binding with signatures, it was glued like a trade-paperback, which is your better quality paperback. There was nothing inside to indicate when it was printed.
It used to be that the Watchtower books had quality binding, but this NWT, because the pages were glued to the binding and not sewn, will after moderate use have pages falling out. I did find an interesting book, which I purchased from Vinnie De Paul, The Catholic Answer To The Jehovah's Witnesses--A Challenge Accepted by Louise D'Angelo. Of interest is the Select Bibliography which includes a number of Wathctower publications. Surprisingly on page 177 is says: "Watch Tower publications have been quoted with permission from the Watch Tower Bible and Tract Society of New York, Inc."