Malware - How did I get Malware?

Each time I remove Malware aka rogueware from an infected computer, I am always asked "How did I get this...?" When I try and explain the concept of drive-by surfing the response is that I never go to any suspect websites. So they think...

The bad guys hi-jack legitimate websites all the time, upload scripts to redirect your browser to a site of their choosing or plant the malware directly on the compromised site to download to your computer.

Now they are using search engines, ie they are seeding their websites to come up first based upon likely searches that may occur connected with an event, the past Oscars weekend created a big spike in Malware downloads. See the link below from the security device maker SonicWall.

https://www.mysonicwall.com/sonicalert/searchresults.aspx?ev=article&id=214&elq=8ff59992d92e456c8129bdb9f43f5c86