I say that not just because that's what I do for a living, but because I've seen some really awful covers on indie published books. (advancedfictionwriting.com)
My worst selling e-books, with awful covers, have sold more than that. (nocturnal-lives.com)
As for Harper's faux historical romances, the majority are mass market tosh with equally awful covers, neither the stories nor the covers depict the eras accurate to historical dress. (goodereader.com)