If a sub doesn't set any terms for a D/s relationship and follows the Dom blindly you can't call her/him human anymore I think... then it's just a sheep without a will of his/her own. And , like John said, that also scares me. I've known a sub like that and she was very happy in the beginning (I don't have to choose anymore, no more clothes, food, etc.. I will follow him blindly). They had there own contract which stated that she was now his, and she gave up her free will (and ofcourse the safety issues). And I expressed my concern about that, and she laughed at me and said "I trust him". Well that was untill he wanted more into the pain area, and she wasn't into pain at all....
He (and she agreed so he has his point) told her that he had every right to do this because she signed the contract, she obviously got scared and turned it all back. Luckely this Dom was experienced and destroyed the contract and both made up a new one with terms. The Dom (a real good friend of mine) just wanted to teach her a lesson, she wanted to give up everything, and he just gave in after alot of talks and discussions....

So to make a long story short... I agree with everybody who replied