Comment by blandflakes

If you have to ask an object what its type is, you're probably about to cast it, and these are operations that the language doesn't enforce that you do together (and so the habit of casting can lead to the habit of casting without the check...). There are times when it's appropriate but generally if you have to ask what type an object is, your code is already starting to smell (because typically dispatching on type is handled by polymorphism, not be the programmer manually implementing it).