Walking down the street in Perth, I always across lawns that have been poorly cut but have the potential to be great lawns.
When lawn mower blades are blunt, instead of cutting the grass the lawn mower tends to rip the grass blades (you'll see a jaggered cut instead of a straight cut of an individual grass blade). Over time, it'll make the lawn look brown. Aswell as this, poorly cut lawns make the lawn really susceptible to disease and fungus.
If you have a contractor who does your lawn and you aren't happy with the results, ask them "Do you sharpen your mower blades?", "How often do you sharpen your mower blades?".