ChUSFA was a university SF club which had a lending library which grew to over 10,000 volumes. Since the membership varied from 25 members to about a hundred - most of the books did not have a chance to get much wear. The club has been defunct for about 20 years, and remaining stocks have been given to me to sell on consignment for the heir, or were sold by me during the past 9 years (often on eBay) - when the portion I was storing ran out of room. I have thousands of books "waiting in the wings" until I can find the time to sort them and see if they meet my standards of saleability. Then I have to grade them and create listings or sell them on eBay if I consider them "high-demand" items.
All were stamped "Property of ChUSFA" on the first inside page and on page 85 (and sometimes on page-block edges: top, side, or bottom.) To improve durability, we often put DJ protectors on dustjackets, or 2" non-yellowing book tape on paperback spines or cover edges. We usually made DJ protectors out of roll-acetate and taped them to the DJ, and then to the book. Later we used DEMCO dustjacket protectors (which are not taped to the DJ and protect it better.) When preparing these for sale, I remove the DJ protector if it shows heavy wear, or leave it on if it still improves the appearance.
As buyer, I would often seek out ex-library hardcovers for our library since they last longer than paperbacks. Those would have typical markings and often have glued-on dustjackets or pockets - any of these are already labeled "ex-library" in my listing.
Since the ChUSFA club was not a "public" library, and their books often have only the 2 stamps as markings - I don't consider them to be what is usually called "ex-library" and do not note them as such. If ChUSFA books have extra markings or tape - I call attention to that.