Of late, I've been finding myself increasingly interested in questions of the form: "Suppose we change this definition in the following way. Does this change break anything?" For instance, suppose we change the definition of a metric space so that $(X,d)$ can be a metric space even when $d$ is defined for values outside $X^2$. So we can say... "Suppose $X \subseteq Y$ and $(Y,d)$ is a metric space. Then $(X,d)$ is a metric space." Would this break anything?
My question is, are questions of the form "would this break anything?" considered to be "real questions"? Is there perhaps a better website for this sort of thing?