If the object is a solid, then "Solid Inspector" should show you where the problems lie. 💭
Then, if not too complex, "Solid Solver" might clean up much of it (and by the same token, could make it worse!!) 👿
However, I have learned that the object need not be a "solid" for SI to help. If you ignore the obvious "errors" such as an open face which is correct, SI will point out the other excess lines and faces where you should be able to determine what is error and what is not.