Stupid shit #1: Dismissing you because you have too many sources. You want to be a good debater so you read the evidence like crazy. A race denier shows up and you link to dozens of studies supporting your argument. It's not like someone's just going to read through hundreds of pages of material, so they dismiss it as a lot of work.
Stupid shit #2: Dismissing you because you don't have enough sources. This wouldn't be stupid if #1 wasn't so common. In this instance, you don't want to overwhelm them with evidence and run into #1, so you just give them one good study, or maybe two, or some small number. They dismiss it, because it's not enough. It's a catch-22.
Stupid shit #3: Assuming without evidence that there's evidence against us while having no desire to link to it. The person looks at your sources and accuses you of cherrypicking because you only link to studies that show a gap - as if the existence of studies showing racial differences would imply the evidence of studies showing no differences. You assure them that no such studies exist and ask them to provide such evidence if it's a thing. At best, they'll show you child studies, since IQ becomes more heritable as you reach adulthood (from .45 in childhood to .75 in early adulthood according to the APA).
Stupid shit #4: Using citations that essentially control for their conclusion as if they are controlling for SES. For instance, there are several proxies to IQ such as what you earn and how well you do on the SATs. Obviously, it should come as no surprise that blacks who score equally well as whites on the SAT are about as intelligent. This is tantamount for controlling for IQ when testing IQ.
Stupid shit #5: Uttering some form of "I'm not a scientist, but let me speak for their consensus." This person concedes that they have no idea how racial differences work, but somehow claims to know what the scientific consensus is. You link to polls saying that it's not the scientific consensus. This usually runs into either #1 or #2.
Stupid shit #6: Operating under the assumption that there is someone somewhere smarter than either of you who would show up and refute all you're arguments, if only they were here. Of course, this does not come with a link to who this person is, what they've written, or what they're argument may be. It's a pure skeptical hypothesis that only exists to shut down critical thought. "I haven't researched the issue, but someone somewhere has and that person both agrees with me and is totally capable of refuting all of your points."
Stupid shit #7: Confusing a scientist's personal beliefs with their data. With a left wing establishment, we either attract left wing scientists or we attract scientists that are intimidated into claiming to have left wing opinions. Either way, most scientists are honest people and publish their data even when it contradicts their personal opinions. Most famously, Robert Putnam found that diversity destroys social cohesion but still wrote that he supports it and thinks it's a great thing. Does his data imply that? Not at all. Does he say that his political beliefs come from his data? Not at all. However, race deniers will do stupid shit by citing his political opinion and then accusing you of cherrypicking if you cite his data without citing his personal opinions.
Stupid shit #8: Claiming that no useful information could ever possibly be gathered unless either several centuries go by or we have some sort of global revolution. These people tend to say that we could only measure racial differences in a society free from racism and discrimination. These people also tend to be of the opinion that racial differences are caused by oppression. Logically, that means that as long as we see racial differences existing, we can't meaningfully test them.
Stupid shit #9: Not providing any sources to support their own view at all. The argument is never ever ever based on who can provide the best sources and the best way to interpret the data. In all cases, you give sources. They come up with factors A, B, and C to test. You give them studies that test A, B, and C. But oops, not together. Or oops, only two at a time. Guess that means there's no way to tell what impact A, B, and C have. Will there be a source showing that A, B, or C ever matter enough to support their viewpoint? No, there won't be any kind of source at all. Of course. And, if you happen to know of sources that examine A, B, and C exactly how they want, then they need D. So you provide that too. Oops, now it's too many sources and you're stuck in case #1.
Stupid shit #10: Citing the Declaration of Independence as a scientific document. All men were created equal right? And not only do they think that's a scientific truth, they also presume that the framers meant it exactly how the person you're talking to would have meant it.