I think everyone at one point or another in their scientific career says: “Why isn’t there a Journal of Negative Results?” Turns out there is, actually, and you could argue that PLOS ONE would also be an appropriate venue. However, it’s worth thinking about exactly why we don’t generally publish negative results. There are the obvious political reasons, one being that by disproving someone else’s work, you have now made yourself an enemy, potentially a very powerful one, and another being that you typically don’t get much “impact credit” for a negative result. But there is a scientific reason as well, namely that it is much easier to confirm a finding than to definitively disprove it.
Let’s say someone had a finding about, say, expression of a gene going up in condition B as measured by RT-PCR. Then we in our lab try and confirm the finding using RNA FISH to measure gene expression. If we confirm the finding, great, done, that was easy! But if we find that the expression is unchanged, then what? In our lab, this is usually when we stop. But if we wanted to publish this negative result, we would not have satisfied the burden of proof. First, someone would say “well, your RNA FISH thing doesn’t work right, at least not in this case.” So now we have to do RT-PCR using their primers and conditions, etc. Then, “well, how do you know your conditions are exactly the same?” Now we contact the authors and try to replicate everything down to the smallest detail. Maybe we don’t get their RT-PCR results. Not useful, because while it might reveal that the original authors were incompetent, they could just keep saying “Well, you’re not doing the exact same experiments as us, so whatever.” Once the result is published, the burden of proof is on you, not on them. Suppose on the other hand that we do confirm their RT-PCR results. Now we’ve just bought ourselves months of work to try and figure out why there is a discrepancy between the methods. Not exactly glamorous work, especially when you already know in your heart of hearts that their result is wrong. Overall, the work required just doesn’t justify the reward, which is only compounded when you factor in the political risks.
That said, there is a type of negative result that would be less politically dangerous, although perhaps not quite paperworthy. Those are the little methods details that are typically buried within a lab’s collective brain. Like “oh yeah, don’t try to use the RNA FISH method in XYZ organism because the high autofluorescence will kill you.” I tried to do that for RNA FISH by setting up a FAQ, and I think it has proven to be useful. If you’re a methods-head, I would definitely give it a try.