I know they say that, but IMO they do a pretty lousy job at it. I almost NEVER see AMS books of relevant genre in the books I want to target. For the record I currently write WWII historical fiction. I'd make more money than royalties if I can get a dime for every time I see steamy romance, dark romance (ie kidnap and abuse type romance), sheik romance, in the line of AMS ads for say, a fiction book about the horrors of the Holocaust.
I've noticed this too, and I think the problem for both of us is that we are in smaller sub-genres. Romance is a MASSIVE genre and, even using relevant keywords, like "historical" for a historical romance, they bleed over into smaller genres and subgenres. And romance is so popular, those books probably get a lot of clicks somewhere
, and the authors have a higher budget, because you probably have to spend more to get any traction in romance with all the competition. So, from an algo standpoint - what the 'zon probably sees is that the mainstream titles get WAY more clicks and are therefore more "successful" ads. I'm in a small sub-genre of romance. I do well when I can get placement on books in my same sub-genre. But the ads on those books are dominated by "mainstream" romance books, because the 'zon sees them as getting more clicks overall (guessing
). Hopefully the algos will continue to learn and refine they way they view "success" from a standpoint of which books cross-promote well rather than just which books are getting overall more clicks.
Again, I'm just guessing here - but it makes sense that this would be the reason that romance titles are dominating subcategories where they aren't the best match.