"wasteful idea" is grammatically correct and can be used in written English.
Example: The company's decision to invest in a new product line without conducting proper market research was a wasteful idea.
The 16th-century blocks were carted away to help build the new China, and Mr. Liang was pilloried as a reactionary for his "wasteful" ideas.
Why is it, she retorts, that these questions arise only in connection with useful ideas, not wasteful ideas?
"Coffee pods are inherently wasteful, and the idea that you can ship them off somewhere to be downcycled doesn't make them any less wasteful," she said.
Her group called the creation of the State Department's Office of Global Women's Issues a "wasteful and unnecessary idea" and opposed the proposed International Violence Against Women Act, because some of its funding could supposedly have been used to "undermine marriage and disrespect women's noble roles as mothers and wives".
In both start-up entrepreneurship and corporate intrapreneurship, pursuing wrong ideas is wasteful of precious time, resources, and energy while identifying the "right idea" to pursue is really hard.
Ms. Quimby rejected the idea as wasteful.
Why not stick to that tried and true method, rather than spend money on another wasteful, albeit good-intentioned idea?
Yet the die-hard believers continue to press for more wasteful spending on an idea that flies in the face of the evidence.
It is enormously wasteful, and it creates the idea that there are quick fix answers to tough problems.
