Yeah, I don't get it. Ads are apparently quite expensive if you're a legitimate author -- but there's an ocean of total nonsense ads for books that I can't eve

Yeah, I don't get it. Ads are apparently quite expensive if you're a legitimate author -- but there's an ocean of total nonsense ads for books that I can't even find via a regular Amazon.com search. Could it be that they're filler generated by Amazon to make your ads more expensive? What other explanation even makes sense?