botcher

This term carries a strong negative connotation, emphasizing not just a mistake, but a pattern of incompetence or a specific instance of clumsy execution that ruins the final product. It is more critical than "amateur," as it implies a failure of skill that leads to a spoiled result.

In modern usage, the word is relatively rare and often feels slightly dated or colloquial. It is typically used in a descriptive sense to label someone whose lack of precision causes a project to fail, often in a physical or manual context like construction or repair.