Perhaps I misunderstood then. I thought the proposal was that the Bullet Clusters dark matter passed through the other cluster without collision and was thus farther to the other side of it than the Bullet Clusters other matter, but that the x-ray emitting gases did collide because they were normal matter subject to electromagnetism (as evidenced by the fact they're emitting x-rays). The x-ray emitting gases were significant, as I understood it, because the gravitational lensing associated with the Bullet Cluster is NOT strongest where they are (despite the fact they appear to be the largest concentration of normal matter).

Singly or in combination; both seem possible, meaning there are no less than three potential alternatives that don't require positing neutrinos are just one tiny part of a whole new class of matter.

The second sentence is the reason for the perception in the first. For my part, I don't think anyone overeager to tell a story unsupported by the evidence, but think many overeager to tell a story that allows few if any tests but radically alters the scientific landscape, in the hopes tests will subsequently become possible and supporting evidence found. The problem with that is it encourages the idea that when such a test is found but the evidence is not the problem must be the test rather than the theory. I mentioned James Bockris down below; it was only when I looked up his name to cite for Texas A&Ms role in the cold fusion hoax that I found he's since claimed to be transmuting elements, but whether it's the Philosophers Stone or cold fusion, if you keep looking and looking for something of which you find not even a hint, rather than not looking hard enough, the reason may be that it's simply not there.

I haven't taken any classes on those specific subjects rather than general physics, no, and acknowledge the large possibility I'm simply not well enough informed to know all the ways my objections have been addressed. However, my concern is that a lot of people who should know better are too invested in dark matter to look for explanations, in the abstract, rather than simply proof of the dark matter they KNOW is there. They have a word for that, but it isn't "science".