How to Find Virus-Free WordPress Themes
You’re a logical person. Right? So, the first thing you think of when you’re looking for a theme is to type “free WordPress theme” into Google’s search box. That could be a very big error. You see loading a WordPress theme onto your server is a very intimate thing. You are basically giving the theme the keys to your kingdom. Themes can, and have been, be infected with viruses to infect your server and turn it into a spam bot.
So what is the right way?
Go to the WordPress repo at WordPress.org/themes/
Search and browse there. Every theme has been vetted by WordPress admins who run the Theme Authenticity Checker and check for viruses and other bad code. http://wordpress.org/plugins/tac/
The other way to find great themes is to use a Theme Foundry that you can trust.
These guys have been in the business for a long time and deliver proven quality themes.