Text not displaying correctly We just recently got new iMacs at work, and we're all having the same issue

 

Not only do we get characters like those in all web browsers, but even some apps!

Is there a way to fix the characters? We've tried changing default fonts without success :(

I'm running 10.9.2

The problem happens in local apps as well, not just browsers. How can I check fonts integrity?
In your Applications folder, there is an app called Font Book.

Open this app and go to File → Restore Standard System Fonts. This will remove any non-standard fonts on your system and reinstall any missing standard fonts.