DTWolfwood said:
Since when does a search engine require 'credibility' to be good?
Pretty much ever since there was more than one of them and they had to start competing with each other? In general, the search engines that don't have "credibility" (i.e. people don't trust them/their results) haven't been particularly successful. In the long run, censored results and things like paid ad placement in search results (as opposed to clearly marked ads that are separate) have driven people away from companies that have tried to pull things like that and to their competitors.
Being able to (somewhat) trust that the company isn't censoring or filtering things or screwing up ranking with paid placement (or at least is doing it less than the alternative choices) does seem to affect the choices of the users, which affects whether or not the company makes money or not. In the long run (which a lot of people seem to be incapable of thinking about these days, which is sad and leads to crap like the economic disaster the world is in now), doing anything to lessen any goodwill or trust your customers have in you will only hurt you.