All foam cushions are not created equal. In foam cushions, there is a great variety of options open to manufacturers. In general, there is what is called high-density and low-density foam. In foam cushions the greater the density the greater the quality. It is important to note that the density has almost nothing to do with the softness of the cushion. The density has to do with how stable the cushion, and how much air is in it.
Generally speaking, low-density foam is poor quality, a high-density foam can be quite good. Shredded foam is almost always bad for two reasons; first it allows in a lot of air, and secondly it can easily lose its shape. Cheap furniture generally comes with low density and/or shredded foam cushions. With a foam cushion air is not your friend because it allows the cushion to lose its shape easily. Low density and shredded foam has the most air in it of any cushion made and therefore are cheaper and less able to create a consistent and long-lasting seating system.
If a piece on our floor has foam cushions you can be assured that it is made with high-density foam. These types of foam cushions very good at keeping their shape and can offer you consistent comfort.