Not sure I follow. The situations I've built appear fine during testing during development. I go to the UI, click the buttons, get the correct result. Test complete.
The type of thing I'm thinking about is when the user does that many many times in a day, but to get to the button that is on one part of the screen which is very inefficient compared to if the button was moved closer to something else so that the UX is improved. Sure, what the dev did "worked", but it might not feel clunky when you test it once or twice. That's the difference that drives most UX<=>Dev disagreements.
Dev: but it works
User: yes, but it sux using it. it can be better for us if change X, Y, Z
Dev: but it works. ticket closed
It doesn't matter if it works while everyone hates using it. I don't care what the devs think. If the user's request is reasonable, rational, and will improve the UX, stop fighting it. This situation is precisely my experience that happens when there's no designer.