About CC

I'm not so familiar with CC license, but I think it is a very good idea for promoting creative activities.
However, I'm wondering that who checks whether the CC license is observed or not. I'm not sure, but actually it seems to be almost impossible to observe. So if there is no system of checking at all, nobody might rely upon CC. Therefore, I think some kinds of system for checking would be required in the near future.
Also I think about sublicense. If someone uses a copyrightable work under CC, can others who want to use the work find out that the work is licensed under CC? If not, the owner of the copyrightable work can not express "Some Rights Reserved" anymore other than licensees.
Since basically I agree with the concept of CC, I hope that CC is used in the way that "Some Rights Reserved."