They can't. If someone has a relation or association proxy named `foo`, and if there were some other attribute/method/property on a parent class with the name `foo`, it would be overridden by this relation or association proxy, making the other attribute/method/property totally inaccessible on this class, so there would be no problem. And if they add a relation or association proxy with a name that matches a column definition, or SQLAlchemy machinery like `_sa_class_manager`, or a Python method like `__init__`, then their code will blow up in their face long before they get here.