Signature campaigns cannot be considered as the major source for earning BTC because they are not jobs, but rewards.
You should understand that joining them still does not guarantee that you will get paid unless you fulfill their requirements, with that said, they should be done as a way of contribution and should not be made just to earn some coins.
Is this your definition of a job? That you need to have a guaranteed payment or it's not a job? What if someone pays me to post but doesn't guarantee I'll get paid? Is it still a reward or a job?
When you hire someone to clean your house and he does it wrong you won't pay him. Does it mean he worked for a reward?
I never said that we need to have something "guaranteed" in order to consider it a job.
And yes, I would absolutely not pay anyone if he/she does the job in wrong way or without any efforts and just for the sake of payment.
You asked that he worked for a reward or not? Ask it yourself, what would be your answer?