I've been pondering this for some time. Bad art is art that doesn't fit the game.
I quite often find people have shoe-horned art into a free game because they "need art" and they found some clip art or CC-NC-BY-SA art they can use to make it look better. If the art fits, then that's OK. If the art is not fitting to the text, I find that jarring.
Is it better to rely on typography and have no art at all rather than bad art?