A Test of a Good Intellectual Interlocutor
There is an easy test to determine whether a person would be a good intellectual interlocutor. Regardless of knowledge, credentials, or intelligence, some people do not make for good interlocutors in the sense that discussing something with them is either not constructive, is emotionally taxing for unnecessary reasons, is not worth the effort for the likely progress, etc. Passing this test does not mean that one is a good interlocutor, while failing it certainly means that one is not. Of course, if one just aims to learn what that person thinks, then this test is irrelevant.
Is the person willing to consider, at least provisionally, that inferences and implications may be drawn from that person's claims that may be unintended and counter to intentions and consciously held beliefs?
If not, then the person is not worth one's time as an intellectual interlocutor insomuch as the person will contest every unwitting implication. At best, the person might be silent about them, or dodge such implications, but I would still count that as "bad"in most circumstances except for maintaining the usual social graces. Typically, such a person would either deny the implication despite the justification, or insist that only that stated claim should be treated, and that it is "unfair" or "unkind" to infer.
If yes, then the person is very likely to be an interesting interlocutor, especially since engaging conversation frequently comes from exploration of previously unthought implications. At the least, the person will not force the conversants to expend enormous effort just to make a point, as opposed to expending that effort elucidating the issues.
Finally, an astute reader might note that my subtitle is inaccurate: this is really a test for whether one is a "bad" interlocutor.