This problem has happened to me before and I forgot how I fixed it. Thus, this warrants a blog post to remind me how I fixed it!
The problem: Editor fonts look weird and the Preferences window refuses to open.
This may be because Java 1.7 is installed or in use. NetBeans on OSX does not work well with this version. You need to uninstall it by deleting the JavaVirtualMachine from the /Library/Java/JavaVirtualMachines folder.
Google for 1.6 to find the download on Apple’s website. Or if it’s already installed, run java -version in terminal to find out what version is active.