Just to clarify...
Crowdflower provides the entire task system. They have a complex system for assigning work, which takes into account a lot of factors including your past accuracy.
"Changing IPs" is something that doesn't trick their system (or ours). For a lot of internet connections, it's customary for you to get multiple different IPs even in the same day. Regardless, all the tasks are tracked by your FC user ID, which stays the same no matter your IP address. In short, you have to remember that your experience on FC will depend on your location, personal demographics, and many other factors. What you see and experience is not necessarily the same as another member. Top task earners tend to have a high accuracy rate and check the tasks panel for new tasks frequently. That, and time/attention to detail, are what will make you successful in task earnings.