How do freelance editors handle a client with bad writing (i.e., head hopping, grammatical errors, etc.)?

This question reinforces the importance of the editor clearly defining with the client at the beginning of the work the editing services available and the scope of the editing work to be done for the client.

There are many types of editing, including fixing bad writing, that an editor can offer. One of these, for example, is developmental editing, in which an editor advises the client as to whether the entire document or manuscript holds together, whether the “storyline” makes sense, the key points are made, and the tone is correct for the subject and audience. Copyediting looks at whether each sentence is clear, well constructed, and grammatically and syntactically correct.

As an editor, I am willing to do whatever level of editing the client requires, but they need to understand up front how much time it will take, what the results will look like, and what it will cost.