You know what I hate? I hate the random little descriptors that publishers like to put on the covers of the super-hero comics. Things like "Crash Test!" on the cover of the most recent Power Girl or "Death at Three Million Feet!" on Batman Beyond. It clutters things up and doesn't really tell us anything about the story. A cover's art, logo, and composition should tell us everything we need to know. And those random sayings obscure that.
Now, I'm okay with certain extra words on the cover. Take a look at this week's Zatanna, for instance. "Bewitched by Brother Night" is similar to those other random phrases. But instead of obscuring the nice cover art it is incorporated into the logo. That makes it feel like part of the composition rather than something that obscures it.
As Todd Klein will tell you in his phenomenal series on comic logos, covers need to stand together as a whole. A great logo and a great cover image are all you really should need to sell the comic. The publishers haven't seemed to have figured this out in the last twenty years...