After interviewing twelve different book marketing services for my upcoming launch, I've developed a vetting process I thought might help others. Here are the key questions I asked that revealed the most about each company's quality:

1. "Can you share case studies of books similar to mine in terms of genre and target audience?" The best companies had specific examples ready, including actual numbers and strategies tailored to my genre.
   

2. "What metrics do you track, and how often will I receive reports?" Top services offered detailed analytics beyond just sales numbers—including audience demographics, conversion rates, and engagement metrics across platforms.
   

3. "What happens if we don't see results after the initial campaign?" This question revealed a lot about their confidence and integrity. Better companies offered specific contingency plans rather than guarantees they couldn't possibly fulfill.
   

4. "Who will be my direct contact, and what is their background?" Many companies use experienced staff for sales calls but assign junior marketers to actually execute campaigns. Ask to meet your actual campaign manager.
   

5. "Can I speak with current clients?" Every legitimate book marketing service should be able to provide references.
   

The price ranges varied dramatically ($800-$5,000), but interestingly, cost didn't always correlate with quality. Some mid-priced services offered far more personalized campaigns than their expensive counterparts.

What questions do you ask when evaluating book marketing services? Any red flags you've noticed that others should watch for?