Why NULL is Bad?

Meh. Using a dummy object doesn't solve the problem of testing if you got the dummy or not. And throwing a specific exception is still an exception, but now more code to maintain, and only for exceptional circumstances (or is it really exceptional?).

Yeah, Null Ref Exception isn't as pretty as a more domain specific one, but the essential thing happens regardless: the program throws as soon as you try to access a member. And if you just pass your results on to another function, that function could be testing its inputs, and throwing your exception there as an explicit ArgumentNull instead of Null Ref.

I prefer less to more code, especially for an error I wont even expect to ever see. If it something I do expect, then sure, make a fancy exception and throw that.

I don't like using null generally, because it results in having to use a bunch of unwieldy if statements. It's much nicer to have the notion of an "empty" object, which supports the same interface as a normal object. Python's lists are a good example of this, as opposed to passing around a bunch of lists or nulls, pass around empty or occupied lists. Both of course support the same interface. This negates the need for a bunch of if statements, which are cumbersome and easy to forget.