A whole ton of SEO. Any keyword from which you can make reasonable amounts of money will be cluttered with sites made by SEO people, who are really good at gaming the index, but really bad at anything else (i.e. actually giving proper information on the keyword you're searching for).

Spam has become an issue again in my native language. For a couple of years Google did a great job at removing spam, but somehow in the past 2 years it has resurfaced.