I work for a small real estate newspaper and many times am given a color print from a desktop color printer to scan by realtors. For true halftone images, I have been using the technique of scanning at an angle at high resolution with descreening on, then rotating and resizing. This has worked well for true halftones, but the images printed from desktop color printers are not true halftones. Any good suggestions here?

The problem with halftones is the regular pattern of dots can cause unwanted patterns to appear. Inkjets use a more random pattern, so the problem should be virtually eliminated. However, if you do see such patterns, the standard steps, such as you already mentioned, would be appropriate.