As of this posting, the campaign clicks have not seemed to convert to sales. But I can say that over 7,000 people saw the ad in passing. Probably, some percentage of them read the ad; and some percentage of them clicked on it. I didn't have high expectations for direct sales from book ad clicks on Facebook, though I thought the ad would have helped me sell a book or two. Possibly it helped me sell a different book and/or caught the attention of one or more Kindle Unlimited subscribers.
I spent $25.00 of my $50.00 ad credit on this the Acetone Enema $0.99 promotion. Depending on the price tag, I may try to boost a post for my invisible children's book instruction manual...once I have something a little more compelling than a book ad to post.