At my previous company, I asked to have a look at the code base before joining. The reason was that this was a system that has been in development for the past 13 years and I wanted to get an idea of how well they handle tech-debt on such an old code base.

The application was developed in C# and ASP.NET and I ended up being quite impressed with how the team handled this. When developing a new feature they made a point to clean up the code they touched to make use of newer language and frameworks features. Also, from time-to-time, there were bigger efforts to clean up specific areas of the code.

This was a 13-year old code base that was in many parts in better condition than many greenfield projects I have seen.

It definitely made my choice to join the team easier.