Here's a thought experiment. While it was prompted by intertubes discussions of evolutionary psychology and some of its practitioners, I take it the ethical issues are not limited to that field.
Say there's an area of scientific research that is at a relatively early stage of its development. People working in this area of research see what they are doing as strongly connected to other, better established scientific fields, whether in terms of methodological approaches to answering questions, or the existing collections of empirical evidence on which they draw, or what have you.
There is general agreement within this community about the broad type of question that might be answered by this area of research and the sorts of data that may be useful in evaluating hypotheses. But there is also a good bit of disagreement among practitioners of this emerging field about which questions will be the most interesting (or tractable) ones to pursue, about how far one may reasonably extend the conclusions from particular bits of research, and even about methodological issues (such as what one's null hypothesis should be).
Let me pause to note that I don't think the state of affairs I'm describing would be out of the ordinary for a newish scientific field trying to get its footing. You have a community of practitioners trying to work out a reasonable set of strategies to answer questions about a bundle of phenomena that haven't really been tackled by other scientific fields that are chugging merrily along. Not only do you not have the answers yet to the questions you're asking about those phenomena, but you're also engaged in building, testing, and refining the tools you'll be using to try to answer those questions. You may share a commitment with others in the community that there will be a useful set of scientific tools (conceptual and methodological) to help you get a handle on those phenomena, but getting there may involve a good bit of disagreement about what tools are best suited for the task. And, there's a possibility that in the end, there might not be any such tools that give you answers to the questions you're asking.
Imagine yourself to be a member of this newish area of scientific research.*
What kind of obligation do you have to engage with other practitioners of this newish area of scientific research whose work you feel is not good? (What kind of "not good" are we talking about here? Possibly you perceive them to be drawing unwarranted conclusions from their studies, or using shoddy methodology, or ignoring empirical evidence that seems to contradict their claims. There's no need to assume that they are being intentionally dishonest.) Do you have an obligation to take to the scientific literature to critique the shortcomings in their work? Do you have an obligation to communicate these critiques privately (e.g., in email correspondence)? Or is it ethically permissible not to engage with what you consider the bad examples of work in your emerging scientific field, instead keeping your head down and producing your own good examples of how to make progress in your emerging scientific field?
Do you think your obligations here are different than they might be if you were working in a well-established scientific field? (In a well-established scientific field, one might argue, the standards for good work and bad work are clearer; does this mean it takes less individual work to identify and rebut the bad work?)
Now consider the situation when your emerging scientific field is one that focuses on questions that capture the imagination not just of scientists trying to get this new field up and running, but also of the general public -- to the extent that science writers and journalists are watching the output of your emerging scientific field for interesting results to communicate to the public. How does the fact that the public is paying some attention to your newish area of scientific research bear on what kind of obligation you have to engage with the practitioners in your field whose work you feel is not good?
(Is it fair that a scientist's obligations within his or her scientific field might shift depending on whether the public cares at all about the details of the knowledge being built by that scientific field? Is this the kind of thing that might drive scientists into more esoteric fields of research?)
Finally, consider the situation when your emerging field of science has captured the public imagination, and when the science writers and journalists seem to be getting most of their information about what your field is up to and what knowledge you have built from the folks in your field whose work you feel is not good. Does this place more of an obligation upon you to engage with the practitioners doing not-good work? Does it obligate you to engage with the science writers and journalists to rebut the bad work and/or explain what is required for good scientific work in your newish field? If you suspect that science writers and journalists are acting, in this case, to amplify misunderstandings or to hype tempting results that lack proper evidential support, do you have an obligation to communicate directly to the public about the misunderstandings and/or about what proper evidential support looks like?
A question I think can be asked at every stage of this thought experiment: Does the community of practitioners of your emerging scientific field have a collective responsibility to engage with the not-so-good work, even if any given individual practitioner does not? And, if the answer to this question is "yes", how can the community of practitioners live up to that obligation if no individual practitioner is willing to step up and do it?
* For fun, you can also consider these questions from the point of view of a member of the general public: What kinds of obligations do you want the scientists in this emerging field to recognize? After all, as a member of the public, your interests might diverge in interesting ways from those of a scientist in this emerging field.