However, a sentence can be:
* Unclear: "The cat sat on the mat, which was green." This sentence could be clearer by saying what was green – the cat or the mat?
* Awkward: "The dog, wagging its tail excitedly, ran into the house." This sentence might flow better if the phrase about the tail was moved to the end.
* Grammatically incorrect: "Me went to the store." This sentence has incorrect subject-verb agreement.
So, while a sentence can't be "inept," it can be ineffective or poorly written. If you're trying to describe a sentence that's not working well, you might say it's unclear, awkward, or grammatically incorrect.