Is the frame well-padded? If you can detect the frame easily through the fabric, the sofa will not only be uncomfortable but also quickly wear in those areas.
Does it pass the "bottom test"? Sit back into the middle of the sofa, where there is the least support, and also in a corner. Is it too soft, too hard? Try out varying degrees of cushion firmness on different models to see what feels good to you. If you're a napper, stretch out.
Do the proportions fit your body? A too-deep seat won't provide the support you need for your back, unless you'll be curling up a lot with your feet off the floor. Similarly, a too-high or too-low arm could cramp your style.
Is the sewing well-executed? Eyeball a sofa to make sure the seams are straight and create a smooth, continuous line, without obvious zigzags or gaps.
How is the flow match? With patterned upholstery, the way the pattern coordinates is key-and referred to as flow match. Poor flow match means stripes are slightly off, for example, and will be a dizzying rebuke every time you look at it.
Are there corner blocks? These wood blocks in the bottom corners of the frame reinforce the sofa by dispersing your weight along the back and side equally. Feel for them when shopping, because chances are, without them a sofa will wear down quickly.
