I have supervised the printing of many brochures, booklets and inserts, and there is a definite art to the printing process, from the choice of paper to the number of inks and varnishes used. There are many different grades of paper and coated paper does not necessarily have to be glossy, there is matte coated as well. Uncoated paper absorbs ink more, while ink sits on the surface of coated paper and can hold better detail and more accurate tones and color. As I stated before, I was disappointed in Steidl's work on the Leutwyler book. It was printed on an uncoated paper that really did not suit it well--the blacks were pretty compressed as well as the lack of subtle tones that I know were missing from having seen some of the images before. In the case of Robert Adams, every print I have seen from him is on glossy paper and I feel that the work should be printed on coated stock, or at least varnished to bring out the feeling of the original. I will have to go back to my copy of American Silence to see if spot varnish was used on the photos. As with coating, varnish can be glossy or matte.
About coated paper, there are (ware) two main families of coatings: the famous (and very expensive) 'couché classique' mainly used for art book printing, and the the more common 'couché moderne'.
Sadly the couché classique is hard to find now as the main manufacturer, in France, had to stop activity more than 15 years ago and was taken over by an Italian producer who finally ceased the production of this magnificent paper because it was to expensive to produce and hard to sell.
Correct me if I am wrong, but I think there is still a Scandinavian manufacturer of the couché classique paper, but I am not certain...
There is non couché too, and this paper was sometimes used only for the text pages in fine art books, as for instance the ones in the famous 'Zodiaque' series published by the great La Pierre Qui Vire publishing house in France.
Couché classique, mostly semi-mate, was very impressive when in combination with B&W photos printed in Héliogravure!
For my book 'Paris Dans Mon Gand', I had to go to Gdansk in Poland to find a printer who could nearly reach the quality of Héloigravure, in off-set, and in B&W duotone plus satiné varnish, but still...