Free themes may pose a hazard for bloggers
The most common keyword for searching themes for WordPress is “Free WordPress Themes”. This will land you thousands of results. The Internet is great, isn't it?
As it turns out, those free themes may come at considerable cost. Siobhan M. of the WPMU blog did a comprehensive analysis of some sites that showed up in Google search results when searching for free themes. The result is rather disturbing: 9 out of the 10 top websites had Trojans or hidden code in the themes you downloaded from them. Source: Why you should never search for free wordpress themes. He writes:
I don't advise uploading themes from random websites directly onto your server – you never know what you could catch! There are some nasty diseases out there …
The only site that appeared to be safe was the Official WordPress Themes Repository.