From what I read so far, such signature campaigns do not look profitable.
it's many times better and more creative than clicking and writing captchas of a faucet.
Thats true signature campaign do not profitable to something like us. Because signature campaign will profitable if your rank is full member and up. That rank have a great and high rates.
What are you guys talking about? How is it not profitable? It's profitable for users because all you do is put an ad in your sig and get paid to do something you would do any way. You get 0.1 for a month on fixed rate deals which is pretty good but if you join something like Bit-x you could earn over 1btc if you put in the work. If you're talking about for the business owners well it's hard to say how effective it is but it definitely gets your name out there.