There are some errors in mechanics, usage, grammar or spelling. Dialogue may have minor errors in punctuation or format.
There are many errors in mechanics, usage, grammar, or spelling. These sometimes make the story hard to understand. Dialogue is punctuated and formatted inconsistently.
Numerous errors in mechanics, usage, grammar, and spelling which interfere with meaning. Dialogue may be hard to tell from narrative, or it may lack essential elements, such as quotation marks or end punctuation.