If the latter is the case, it would be a Heisentool, where the attempt of using it changes that which it is supposed to observe. :-P
Which is why I don't use the pointer explorer when I'm trying to clean all instance of a class out. Instead:
TheClass allInstances anyOne chasePointers
TheClass someInstance ifNotNil: [:obj| obj chasePointers]
Ah, I will start using #someInstance, but typing ifNotNil: is a lot more work than closing a debugger when no more instances. Besides, wouldn't the Block Context's var, "obj" be another possible reference that #chasePointers might pick up on?
ifNotNil: is inlined. It is equivalent to this, but saves the temp decl, which is why it's so nice.
| obj |
obj := TheClass someInstance.
obj == nil ifFalse: [obj chasePointers]