Most cover problems are not dramatic software failures. They are reasonable decisions that stop working when the design is reduced to a marketplace tile, extended into a print wrap, or compared with the books readers already buy.
Everything is competing
A large title, bright subtitle, detailed illustration, review quote, badge, and ornate border cannot all lead. Choose a primary reading order and deliberately quieten the rest. At thumbnail size, the reader should meet the title shape and one visual idea before secondary copy.
The genre signal contradicts the story
Elegant script, distressed capitals, illustrated couples, symbolic objects, and cinematic landscapes each carry expectations. A technically attractive cover can still lose the right reader if its visual language promises a different tone, age category, or level of intensity.
Effects are repairing the wrong problem
Heavy shadows, glows, outlines, and dark overlays can force text to remain visible, but they cannot create a coherent composition. First move the crop, simplify the artwork behind the title, adjust the type width, or create a quiet field. Add an effect only when the remaining collision is specific.
The final format was treated as an afterthought
Low-resolution art may look clean in the editor and fail at 300 DPI. A front image may look complete while the back copy enters the barcode area or the bleed ends in a visible frame. Test the real export dimensions, not only the attractive preview.