There are over 1,400 themes available at the WordPress Theme Directory. There are a lot more elsewhere online. Although Leland of Themelab blogs Stop Downloading WordPress Themes from Shady Sites, the point really should be: be cautious when downloading any themes ANYWHERE.
Some of the things to look for:
– Encrypted code
– Inability to edit layout to fit your own means
– Link spam that have nothing to do with your site or may be linked inappropriate websites in the footer
– Malicious code that could open your server to attacks or your own computer to viruses
“Free” is without expecting anything in return. It is great to leave a link from the original theme creator on your site so your visitors will be able to use the free theme too . However, it is a nuisance to have all the other frills, and not-so-frills. It might be difficult to accept that you could either pay for a safe theme or download a free one from a trusted source, but it is important for your internet safety and the safety of your readers. It also alleviates future problems if the layout no longer functions due to WordPress upgrades and code changes that might break or make older themes buggy. Having to hurry and fix a theme issue is not fun, and if you have a free theme from a untrustworthy site, you will be scurrying to get a new theme up.
As a note: As for malicious code, if you are a shared hosting client, you might have to hope your web host is forgiving as they will have to fix the mess in case you have been hacked. Most web hosts have in their usage policy that it is your responsibility to keep software update and avoid using questionable programs, and that even includes your themes. You could risk being terminated and no refund of your money.
Although not everyone has their free themes uploaded to the WordPress theme directory, if you have found a theme you like, go to the WordPress support forums or ask anyone in the WordPress community if a certain place can be trusted and can vouch for it. Like visiting any site, if you cannot trust it, why download?
Are there any sites that people should avoid?