Just because you "should be able to" doesn't mean you'll want to. If the job is going to be unpleasant because the code base is steaming dumpster pile of garbage, that would be nice to know. Maybe you'll appreciate that kind of challenge, maybe not.

These are good points... I certainly value these factors as well.

And agree with you, to a point, that an engineer "should" be able to work with any task or codebase. We aren't primary care doctors in a community clinic who are obligated to treat every person who comes through the door.

I know myself pretty well. I know the kinds of environments in which I am most productive. I know the kinds of environments that I find to be a tedious and mentally exhausting slog. I prefer to avoid those. Some codebases are just awful to touch. I think it's OK to have some boundaries around that.