Vit C is one popular active I decided to skip, for various reason: I am not a skincare professional, but I've learned that vit c is highly unstable, it goes bad quickly and easily, it is hard to formulate into an elegant product because it does not mix well with water and on top of that it can often irritate the skin and cause pain like you said, and rashes etc. There are other ingredients that can deliver similar brightening/spot lightening results, so it just seems like a lot of pain and not enough gain in my personal opinion.
I recommend watching Lab Muffin Beauty Science and Dr. Dray for a breakdown of the science!
Secondly, why does Caroline hate Creighton's? I've used some of their body products and they're pretty standard for the drugstore..