Frazetta Conan the Buccaneer original cover
Paperback cover, May 1986 reprint shown below
Backing up Ellie Frazetta's (Frank Frazetta's wife) claim that publishers realized that Frazetta paintings not only helped sell books, but sometimes constituted the only reason some folks bought the books at all, is exemplified by this 1986 handling of a reprint of Conan the Buccaneer (which alter morphed into Conan the Destroyer). Notice that the back cover doesn't contain any blurbs or reviews or a synopsis: just Frazetta's painting repeated sans logo and author credits.
More Frank Frazetta
Conan the Phenomenon - Dark Horse Conan historian Paul Sammon looks at all the stages of the character's development, with commentary and archival material from the most integral players in that history, in this must-have book for anyone who's followed the barbarian through any of his incarnations.