You can and you should. A terrible cover could be a reflection on the writing or the story line. A great cover means the writer took the time and money to insure the cover was professional looking and the book probably had that kind of attention to detail too. Here's two examples of cover makeovers.
I see a great cover and think immediately that the author is probably award-winning, uses an editor, invested some money into making the book the best version it can be. Or that the writer has an agent and contract with a major publisher and they paid for an awesome cover, thereby telling me that the writer is 'good enough' to have an agent. I know, I know, times have changed with Indie Authors but I'm still living in the stone age in my sub-conscious and I can't make those thoughts go away.
That's not to say that there aren't some wonderful books out there with strange/bad covers. I have read some and written 5 star reviews. Those books that I'm thinking of now have new covers. Better covers. One that comes to mind that has a weird title and had a terrible cover is The Girl From Long Guyland. This is the new cover (which isn't much different or better than the first one) but in my estimation it doesn't do justice to the book.
It was a great book especially if you grew up in the 60's and 70's and experienced the hippy days.
Another book that I loved but wasn't sure about the cover was The Dream Student by J.J. DiBenedetto.
I've changed covers many times. Just this morning I received the new, improved, souped up cover changes for my novel The Dream Jumper's Secret. I had my wizard cover artist Jen Henning add more suspense to the photo, make my name bigger, establish a full-time font for my name to be used always, change the tag line, and add some praise/small print. I love it!
For my first cover in this series, The Dream Jumper's Promise, I asked her to add some words too. The New York/Big Five Published look has lots of fine print usually and that's what I'm going for. I did this because I'm a Cover Snob and totally judge a book by it's cover. I look for little print so I can zoom in to see who endorsed their book, what awards were won, what's being said.
Here's an example of a terrific first cover that I think was provocative and unique with a single female on the front. She eventually went with Hachette for this series and after they re-released her indie series she got the standard couple in a state of foreplay for the new cover.
Font is important, placement of the name, the title, how much stuff is junking up the page, or how uncomfortably simple the cover looks.You want the cover to promise the reader something whether it's a crime, a romance, an adventure or even if it's just why is there a rose and a screwdriver on the cover of this book.
The cover models don't have to look exactly like the characters they represent but it shouldn't be a totally misleading promise. The hero in my suspense Necessary Detour has longish hair and looks similar to Sawyer on Lost. You can see that they went with a photo that didn't match the description except for hair color. But then if you sign a book over to a publisher, you don't get final say on the cover. Not really. If you have control over your cover, don't put Harvey Stables on the cover if your hero is slightly lean with blonde hair and glasses. Just saying. Or don't have a provocative cover of a bloody rose and knife if your story is an HEA romance, not crime.
I highly recommend using a cover artist and save yourself about 4 months of obsession with iStock photos, Dreamstime Photos, Hot Damn Photos and every other stock photo site in the world. You will drive yourself crazy if you don't have a very specific idea of what you're looking for and then stick to it. And that's time you could be writing, which is probably what you do well in the first place. Not cover design. Most designers will work with you and your vision anyhow. You can give them a thumbs up or down on anything they suggest. I fear I drive Jen Henning crazy but her emails always make her sound like Mary Poppins. Poor thing.
Covers matter greatly. As the Killion Group said recently in a workshop about covers, it's like the first date your reader has with your book. Show your game face. Put the contact lenses in, brush your hair, present yourself in the best light possible to insure your date doesn't stop at the door when they suddenly remember their grandmother is having surgery and they have to leave.
Kim Hornsby is the author of several full length novels on Amazon and other venues. Her latest series The Dream Jumper will release a third book in February or sooner. Her Christmas romance, Christmas in Whistler will launch December 1st.
Visit Kim at www.kimhornsbyauthor.net