you don't go asking menu questions until you're face to face with the lady, and I agree.
She probably looks at and/or smells a guy and decides in the moment whether to use the cover with him. So be groomed, washed and polite.
What her reasons are doesn't really matter. They're her reasons and important to her and whatever she does with you, don't fight with her about it. BB IS better, but CBJ isn't the end of the world and you'll probably still get off.
Another thing to consider is that some guys aren't totally honest in the reviews. There are endless discussions about why guys lie in reviews, but the point is it happens.
If it's that important to you still, PM some of the guys who reviewed her and ask if they know why she decided to go cover or not, if they paid a premium, etc.
Based solely on what I've seen said around here by a lot of people, I don't recommend asking her about it until you meet her.
If she has a website, read it completely. A lot of ladies are very clear about this issue on their site.
Good luck.