I've had experience with Mary's certification and others across Canada. With the issue you just brought up, the companies in name only, the certification will ensure that doesn't happen. Our staff were the site visitors, as Mary said, so I'm well aware of what they're asking for.
One of the first things they're looking for when they go into that business is that the woman is the decision-maker and is the one actually running the business. It's very easy to tell when you visit a company whether that person is running it. One of the things that the certification will do is to move away from the name-owned businesses.
I don't think you'll have an issue with that early on, but as you start to purchase from smaller diverse businesses, then you will maybe see that, and you will need to look into making sure they are verified.