My potatoes have turned sweet and I'm not sure why. They have been sitting at room temperature for a week or longer. Is there any hope in getting the sweetness out of them?

The short answer to this unfortunately, is no. That is to say, if the so-affected potatoes have already been prepared. However, there is hope for the remaining, unprepared overly-sweet potatoes (which is typically caused by storing too cold, 41° F or colder, for too long a period). In this case the starches within the potato convert to sugar and this affects the cooking chemistry, and results in the sweet flavor you describe. To recondition, store cold-impacted, unwashed potatoes in an ambient (room temperature) area, protected from light. Such as inside a cupboard or in a pantry. Allow the potatoes to sit for about 10 to 14 days. This is usually be enough time for the potatoes to ‘burn off’ the excess sugars within and return them to a manageable cooking chemistry with normal flavor.