I don't think they are purposely being sneaky, just that I can see why readers would feel like they were.
But if you don't read Christian Fiction, you probably wouldn't know that.The Christian publishers have all existed for many years (although nowadays many of them exist as imprints of larger mainstream publishers) and they have a dedicated following of readers who are familiar with these publishers and the types of books they produce.
That's a pretty big expectation. I do think Amazon users should just take a closer look at the categories or book summery to find out if it's CF but to expect everyone to research and memorize all the CF publishers and authors out there is a little unreasonable in my opinion.It is incumbent on the reader who does not want to read these types of books to learn who the Christian publishes (or authors) are and then avoid those publishes and authors.
All I'm saying is that publishers could make a little more obvious when a novel is Christian Fiction.