Common sense needs to be simple, because it sometimes needs to be fast-acting, but it is also by necessity complex. It’s like a net of understanding that gets thrown forward onto immediate experience, with feedback loops working to get the right relationship between knowns and unknowns. This is what confidence men are dealing with when they run a con on someone. They have an intuitive, skilled understanding of the common sense working in someone and how to get around it. They do that by gaining the confidence of the mark.
A mark is by definition someone who has been marked for a con game. The confidence man, the con artist, works out of his own absence of conscience. And so one can infer that common sense sometimes relies on an expectation of good faith in others, which requires conscience. Indications of bad faith, by extension, should revise someone’s common sense vis a vis a particular person or entity.
For instance, a store where the workers and managers all have bad manners should put a customer on alert for untrustworthiness. In politics, given what people are willing to support, common sense seems to be all but permanently suspended. (Politics is largely a region that lies outside the reach of common sense.)
The key component of common sense is the moral sense, which forms conscience, where an individual looks to advance good and avoid evil.