Inspect the frame by turning the piece over and carefully tearing out the bottom and the back. Quality frames are made of solid wood with few knots. The frame should be doweled or screwed together and not stapled and glued. Glue may be used, but this should not be the only thing that holds the frame together. Check for broken wood and loose joints. Some frame pieces may be replaceable, but an overall deteriorated frame may be an indication that it is not worth saving.
Inspect the springs of your sofa or chair. Are they sagging or broken? This may not be a deal breaker, however, broken springs may increase the price of a reupholstering project. Check with the upholstery company to determine if it is capable of fixing or replacing broken springs.
It is likely that the filling in an old couch or chair has broken down. More often than not, all of the filling and padding will have to be replaced and cushions remade. The upholsterer may recommend upgrading to modern padding materials with better density and overall durability. You will have choices in the density and quality of padding material. You may also have the option of switching from loose back pillows to a solid back with additional padding on the back.
Is the style and scale of the furniture consistent with your current decorating goals? This may not be a problem if the upholsterer can modify the piece with minimal expense. A different fabric along with a few embellishments can significantly change the look of a piece. A button-tufted back may be turned into a sleek smooth back. Legs can be changed and previously exposed wood may be covered. You have hundreds of fabrics from which to choose when reupholstering a piece of furniture, whereas a new piece may have a limited fabric selection.