Answer

There is a series of columns on the site that deals with the question of what philosophy is. But I don’t suggest there a methodological criterion for philosophical discussion, because to the best of my knowledge there isn’t one. The texts I would try to read are those that have meaning and are grounded in logic. Indeed, such an amorphous and flexible definition allows a lot of garbage to get in. We can plainly see that this is the situation. But it is enough to disqualify quite a bit of that garbage. See, for example, the column about carrying out justice on the French and their helpers.
Such a criterion obviously won’t help you before you’ve read something, in order to know whether to read it or not. Here I would adopt ad hominem criteria—that is, if there is a person whom you’ve seen produce garbage or nonsense, don’t try other articles and books by him.