While in general engineers should define things, so that we can be clear about what we mean, there are plenty of things that are difficult to define that way. Love, happiness, satisfaction, for instance. You might argue "well those are emotions so they don't count" but you don't need to go far to find some more. What is the "perception of red"? What is the sensation of temperature (thermoception) or my sensation of my body in space (priprioception)? The sensations of these things are difficult to define--even if we have good explanations for how the physical world induces them--but they are experienced nearly universally by humans and we most people don't feel the need to define them to find them to be useful ideas.

If you don't have any taste, you could work with someone who does have taste to do the interface design. Or you could copy popular patterns and designs, but that might lead to a worse experience if you copy the wrong things, or try to bend your project to fit a popular design that doesn't quite fit.

If you like it the way it is, then guess what, you do have taste, tell them to fuck off and just keep it the way it is.

The difficult part is being honest with yourself about why you like it the way it is. If you do honestly like it for what it is, then others probably will too, no one is really that unique. If you like it because you put a lot of effort into it, then you're just letting your emotions lie to you.

> It's kind of useless if it can't be defined

That's just the programmer/logician in you screaming "unknown feeling!" :)

Programming (for me at least) is as much of a creative endeavor as it's one of logic. You can train yourself to at least recognize "good" from "bad", even though it's much harder to teach yourself how to go from "blank" to "good", or even being able to actually define why something is better than another thing. Sometimes it's literally just "vibes" and that's OK.

If you're unable to train this feeling in yourself, maybe the best course of action is to find someone you can tell is able to better use that particular skill, and ask for their feedback.

I'd argue its not definable globally, but within whatever niches you're a part of it probably is. The reason I didn't try to define it when I wrote this is because the question stands good taste "to whom".

So like you definitely probably can get pointers from people in your specific niche and if you've been in that niche long enough you've probably developed some level of taste and feeling for what people in that group like and need.