Google Search Result Warning
I just found some interesting with Google helpful tool when I searched these keywords “tennis directory” using FireFox browser.

It shows the sentence “This site may harm your computer.” It is helpful to warn their users about risks, viruses, adwares, malwares, spywares, trojans, hacking activities, and harmful softwares which will damage user’s computers.
If possible, I think they should not indexed these harmful websites which get noticed by this sentence for a few months (You also warn website owners clean their websites). Then nobody will be not hurt by this error or some serious problem.
Though other search engines will still indexed them. But if Google starts first like this. This will help guide them to do some good features for their engines.