What interest could you have in their search algorithm? Or should I say, why should they disclose it? It would only allow SEO spammers to game the system so muc

What interest could you have in their search algorithm? Or should I say, why should they disclose it? It would only allow SEO spammers to game the system so much easier. This would fill the top results with crap so I would think it's in everyone's best interest that the algorithm is kept secret. Also the quality results are what separates Google from the competition. Are trade secrets not allowed anymore?