I'm not sure even "Senior" software developers will be able to understand badly written code at first glance. However what experienced developers will most like

I'm not sure even "Senior" software developers will be able to understand badly written code at first glance. However what experienced developers will most likely do is make a copy of the code, open it up in a good IDE add a breakpoint and run it. Add your own comments to the code as you go along and figure things out. And don't forget to take some notes separately too. As others have mentioned in the comments, you might be suffering from "imposter syndrome" but don't let it get you down. Some of the best out there have been through what you're experiencing [0]. [0] https://www.hanselman.com/blog/how-do-you-even-know-this-crap https://www.hanselman.com/blog/how-do-you-even-know-this-cra...