I seen some sites where no matter what "niche related" keyword i type they show on first page. but the result of their content is nothing but another search.. for example if i type cheap ford focus i see their page and click it take me a page on their site with search results about ford focus... 1- what you call these softwares? 2- isnt it a call for ban due to blackhat techniqques?
Maybe they are customized scripts or search pages of that site getting indexed. This is not a black hat technique but yes some sites over do it only google knows why they are ranked.(maybe due to quality backlinks)
It's probably that Google notices the search term being something generic and tries to bring in something generic in that manner, too. So it might be because of too much content match on a single term, just a speculation though.
If the searchers input is too broad then the search will provide generic terms that will lead to specific data and this is because Google is trying to understand the searchers intent and gives them the most related terms according to the query.