A study conducted by AV-Test, an independent German testing lab, found that Bing returned over five times as many links to malicious sites than Google did. The study, conducted over 18 months, found out that malware sites are still appearing as top search results, even with all of the work Google does to keep them from appearing.
The entire study examined around 40 million different websites that were returned from seven different search engines. Google did quite well in the study, returning just 272 malicious results in 10 million. Bleko did even better, though not by percetnage. Bleko returned just 203 out of three million results.
Bing, on the other hand, returned a massive 1,285 malicious results out of 10 million. Yandex was one of the worst offenders, returning 3,330 malicious results out of 13 million pages.
Unfortunately, the creators of malicious websites are using search engine optimization tricks, causing malicious websites to sometimes be the top returned result. Just remember to be safe when searching the web.