As I use piwik to analyse my site, it can show me some visit stats that I never see before.
In the report of piwik, I can find out where people from before they come to my site.
So the interesting things are coming.
When I look at the keywords that search engine provided and contrast the page they visited. I found that only google do the right job. Other search engines are always lead people to the wrong page.
You just need to know is that google has its own smart way to understand what you are looking for, and give the right result to you. And other search engines, hope you will never use them.