Changing quality of photograph

I do engraving and am receiving a lot of requests to put photos, usually people or animals, on wood, glass, etc. A poor photo to start with means you work like crazy and may or may not get a usable image. However, the customer does not recognize the amount of time this takes and is unwilling to pay for it. After several times of spending 10-20 hours and charging for 3 or 4, I now require at least a well detailed photo. Contrast can often be adjusted, touch ups done, and cutouts take care of a lot of background problems, but it really depends on what you start with. Up to recently I was willing to put in the extra time because I charged it up to a learning curve. But the others are right - garbage in cannot result in quality out. What makes a beautiful picture, does not necessarily make a good graphic.