A large part of taste in research is deciding what not to work on. You might choose not to apply method X, even though you don't really understand it, because it has a reputation for being fiddly and difficult to get right. You might choose not to work on topic Y because you think that even though there's a lot of people writing papers about it, its goals are too ambitious to ever be met. This extends all the way to entire fields of research. I could name a few popular fields within computer science — with active research communities, large amounts of external research funding, leading researchers with fancy prestigious awards — that I suspect are being investigated in entirely the wrong way, and that I personally think are currently pointless.
I could name them. Will I? No.
Why not? To protect my career? If I am honest, probably in part yes. But what I tell myself is different. The real answer, I think, is that my opinion of these areas is poorly informed. Because I think these areas are uninteresting, I haven't studied them carefully, and so I don't know how they've attempted to address my naive objections. It would be arrogant and professionally irresponsible to publicly denigrate the hard work of many people without having even bothered to read it.
This leads to a paradox. It's impossible by definition for me to become better informed about these areas, unless I decide to actually start researching them. In order to be fully confident that an area is uninteresting, you need to study it — and that study itself is part of doing research! But you can't do careful reading on every research area that seems bogus at first impression, because then you would do nothing else. Instead, you have to take intellectual shortcuts, and do the best you can with limited time to think. Those research areas that smell a bit off, you ignore them until either they die out, or a major success forces you to reevaluate. Part of taste in research is deciding what to study, and what to ignore.
This is the paradox of taste in research. Your decision of what not to work on is, by definition, always ill-informed.