A code generator is a type of compiler. You don't worry about how pretty the compiler output is, you just work with the source code. Using it and then hand-modifying the output is often harder than just writing it from scratch in a form comprehensible by humans, and means you can't use the code generator again without a lot of work, since you'll have to apply the same changes to the same incomprehensible code accurately.
Therefore, they can be fine if they're part of the build process, and documented as such. The input to the generator is then the source code, and whatever it produces is intermediate results, not to be messed with.
However, if somebody's using one to produce incomprehensible code that's supposed to be used as source, then that person's producing bad code. It doesn't matter if the person is producing bad code mechanically or by hand, it's still bad code, and you still have a quality problem with it.
Therefore, you need to treat this as any other developer cutting corners and writing bad code. I don't know how you handle that at your shop.