Over the years I have come to realize that there is one trait that you need to look out for when hiring developers for your product team.
It all boils down to having a solid “attention to detail”.
The developer should love to fine tune, nurture and optimize code. If something is not right, they should feel uncomfortable and fix it before it adds to the technical debt of the software. Bottom-line, they should deeply care for the code.
In fact, I ask a few questions in the interview to gauge their attention to detail. You can even do a quick back and forth via email. The way they write their email and answer your questions tells you a lot about who they are and if they care about the minute details.
95% of the people I interview don’t fit working in a product environment. It is tough to find the 5% (cause these are really good developers) but when you do, these people will count for nearly 3–5 average developers. And, you rather have a team with a few really good developers than many many mediocre ones.