Every week, over 10 million users encounter harmful websites that deliver malware and scams. Many webmasters for compromised sites are unaware anything is amiss. When Google works directly with webmasters during critical moments like security breaches, we can help 75% of webmasters re-secure their content. When we emailed webmasters, we included tips and samples of exactly which pages contained harmful content. This, combined with expedited notification, helped webmasters clean up 62% faster compared to no tipsusually within 3 days.”]
Source: https://ai.googleblog.com/2016/04/helping-webmasters-re-secure-their-sites.html