I hate them because the install a back door Trojan
I hate them because the install a back door Trojan into your computer via the flash component required to run their game. If you do a scan by spybot or superantispyware. It will detect over 65 entries. This backdoor allows zynga to collect your passwords almost like it was a keylogger, and also give them access to your computer.
So there stuff is malware, and virus ridden.
In fact you click on some of those links in facebook and your virus scanner will pop up over adn over.