How to detect bad UI design [closed]

1. What would you consider as a UI design failure on a newly launched product?
2. Can bad UI design have good UX?
3. How can UI designers avoid most common errors?

What would you consider as a UI design failure on a newly launched product?

What would you consider a UI design failure on a newly launched product? From prioritizing aesthetics over usability, to overlooking accessibility, there are plenty of examples of bad UI design.

Can bad UI design have good UX?

Users may love the product with bad UI yet good UX because a smooth and intuitive customer experience prevails the interface beauty. It doesn't mean a pleasant interface won't influence users' attitudes to the product, though.

How can UI designers avoid most common errors?

Be consistent, never use different primary navigation on other pages. Go for different solutions for mobile and web. Think twice before sacrificing the fixed menu during scrolling for aesthetic reasons. (However, it's also a common mistake to make the sticky header too large or stuff it with unnecessary content.