This is just a selection of the gay pulp titles available on ebay at the moment. I had a fun few minutes tracking down some of these wonderfully sensational paperback covers. The 'genre' of gay pulp is actually more a matter of presentation than of a similarity of style. These books, dating from the 50s and 60s range from out and out erotica, to faux documentaries/scientific studies, to real literature such as the work of Rodney Garland and Andre Tellier. They are a great way to get into collecting gay literature as they are, for the most part, still quite inexpensive. For the works of Phil Andros (aka Sam Steward et. al.) you have to pay a little bit of a premium now, on the back of a biography and the publication of his journals.
Ian Young's Out in Paperback is a brilliant analysis of the iconography of these book covers based on a huge collection that he put together at a time when they really were still very cheap, (although why a copy of Ian's book on Amazon should be 190USD I have no idea!) His analysis brings up some fascinating recurring themes in the visual presentation of this kind of book.
And moving away from the visual, how interesting that this small and random sampling should have two 'twilight's and one 'midnight' in the titles. Clearly the covers, the titles, they were all part of a narrative about homosexuality in the mid-20th century and that, in the end, is what makes these books so fascinating.