Hi Ginger,
They may have been mixing up memory foam with latex. With polyfoam and memory foam, density is the single biggest factor in its quality and durability but unlike memory foam and polyfoam … with latex density isn’t a “quality spec” and density varies with the type and softness (ILD) of the latex (firmer has a higher density and softer has a lower density). With latex the type and blend of the latex is the information you would need (see post #6 here about the different types of latex) and density isn’t something I would pay much attention to unless it’s the only way to estimate the softness of the latex if you aren’t testing it in person (which may be the case with some types of Dunlop latex).
Phoenix