Is there a general rule for when you should use 'make clean' instead of just 'make'?

Question

I am writing a multiple-filed program right now, and apparently running only 'make' (as one would intuitively think needs to be done in most situations) for some reason causes my program to fail. I guess I can provide more detail of the problem, but the important thing is that it does run when using 'make clean'. So I was wondering if anyone knew the general rule of thumb for running 'make clean' instead of just 'make'