There are no "bad" OOP features. Smalltalk is the archetype of OOP. There's nothing bad about programming in Smalltalk.

However, many programmers (far too many) abuse and misuse OOP because they fail to fully understand the paradigm. A lot of this misunderstanding comes from learning OOP with languages like C++, Java, Python, etc.

When done right, OOP in Smalltalk is very powerful and productive. That's why I always, always recommend learning OOP with Smalltalk before using any other OOP language.