My best counsel on this point is:  

SWYMOD:   Say What You Mean Or die

• If truth-or-falsehood is known and is an appropriate response, your code should return one of those values.
• If “nothing” is an appropriate thing to return, your code may return undef. But, by the same logic that says (in SQL) that “NULL is not False; it is the absence of a value,” you should not return “the absence of a value” when what-you-mean is “I do have a value, and that value is False.”
• If the situation that you have just encountered “cannot happen, but it just did,” then you should IMHO never return anything. You should die, or better yet, use one of the carp functions such as croak.

In this way, when you do “return something,” what you return is the most meaningful and descriptive response that you could have returned. And if not, you do not return at all... thus forming a useful social-contract that, if your function does return a value, that value can be relied-upon without further testing of return-values and so forth. Exception-handling blocks are efficient and cheap. (Obviously they cannot be used in all cases, e.g. for historical reasons.)