Most folks may not know it, but the BBB is toothless for the most part. In fact, some BBBs will even permit an expelled member to rejoin immediately under a new corporate name thus giving the expelled member a clean sheet with the BBB.
Furthermore, BBBs only handle complaints from consumers. Authors are considered businesses. Therefore, most BBBs will not handle their complaints because that's a business to business dispute. BBBs weren't set up to handle those. Consequently, when a writer does a search of BBB records for publishing houses and other writing oriented businesses, it's to be expected in most cases that the search will come up with a clean record. Consequently, a lot of scams deliberately join the BBB and exhibit the emblem on their letterhead or website.
By the way, here's something else many consumers don't know about BBBs. When you look at statistics for closed cases, you're not seeing what you might think it means. That's because many BBBs consider a case closed when the business complained about makes contact with the complaining consumer. The complaint doesn't have to be resolved. Only contact is required. Once that's accomplished, many BBBs consider the case closed. They did their part. They assisted the consumer in contacting the business. Now they can slap themselves on the back and smile.
Does that mean the BBBs never resolve anything? In rare and extreme cases, the BBB will but such instances require extensive documentation and show a deliberate disdain for consumers before the BBB will take any action. Unfortunately, in most instances, that's going to be expulsion from the BBB.
So, just remember that BBB membership is not a clean bill of health for any business and especially not one that deals with authors. If anything, BBB membership should be considered a red flag that causes the author to wonder why a business, such as an editing service, that does business only with other businesses would even need to be a member.