Judges distinguish between minor vibrations and bone-shaking tremors, normal barnyard smells and sickening stenches, and puffs of dust and blizzards of topsoil. An activity that overcomes extreme defensive measures taken by neighboring properties will be declared a nuisance. Nocturnal noises interfering with sleep can also sound the death knell for a particular activity, especially when there is evidence of widespread community dissatisfaction and not just a single complaint. An environmental injury will not be declared a nuisance unless it outweighs the utility of the activity. Determining the weight of a particular harm is often difficult for courts.
Judges are human, and humans disagree on just about everything, including nuisance law.
The easiest type of case for a judge involves an injury inflicted solely for the purpose of causing harm. A fence constructed with the intent to obstruct a neighbor's view will always be declared a nuisance. No socially redeemable value is assigned to animus and hostility. Most cases, however, do not involve a nuisance created by adverse motivations. For instance, polluters usually produce useful products integral to a local economy, and the market value of an injured property is rarely greater than the business investments made by the polluter.