It is alowed from adsense to put high paying keywords in content with content with other keywords! I mean for example in text for music to put some words for banking or credit cards?
Im not 100% sure, but i think adsense would see that as misleading advertising or something! Google is pretty strict with their rules, so a good rule when it comes to adsense: "If your not sure wether it's illegal or not, it probally is!"
https://google.com/adsense/support/...8182&ctx=en:search&query=hidden&topic=&type=f The very last paragraph... If you display adsense ads, you're required to obey the webmaster guidelines. The webmaster guidelines do not permit hidden text.
You could try writing an article on the high paying subject. However, adsense often takes the content from the URL and meta tags, so you might find it hard to get high paying ads just from some extra added content.