If 1) there's a solid engineering case to be made that this code is bad, 2) the code does something that's important, and 3) the company doesn't want to fix it, then you can be confident that the company also isn't interested in investing in the things that you as an employee would want them to be. I would expect work in general to be unenriching, raises to be smaller than at other places, and other benefits to be not as good. This could be an early sign that spending time with this employer is bad for your professional growth.

Edit: definitely kick the tires a bit by seeing if this situation is typical for the company, or if it's an outlier.