* Personal opinions or beliefs: A research paper requires evidence and analysis, not just a statement of personal views. For example, "Why I believe cats are better than dogs" is not suitable.
* Topics too broad or too narrow: A topic needs to be focused enough to allow for in-depth exploration within the constraints of a research paper, but broad enough to allow for meaningful analysis. "The history of the world" is too broad, while "My cat's favorite toy" is too narrow.
* Topics that are purely speculative or based on unsubstantiated claims: Research requires evidence. Claims that cannot be supported by evidence from credible sources are unsuitable. For example, "The existence of aliens who visit Earth" without proper scientific evidence.
* Topics that are primarily descriptive rather than analytical: A good research paper requires analysis and interpretation of evidence, not just a summary of information.
* Topics that have already been extensively researched and offer nothing new: Unless you have a truly unique perspective or methodology, a rehashing of existing research is unlikely to be accepted.
In short, a good research paper topic needs to be researchable, manageable in scope, and offer the potential for original analysis and contribution to the field.