The exact definition of spiciness is debated. Specifically, the orthogonality of the density with spiciness and the used scaling factor of potential temperature and salinity. McDougall claims that orthogonality should not be imposed because: 
* There is no physical reason to impose orthogonality. 
* Imposing orthogonality would necessarily depends on an arbitrary scaling factor of the salinity and temperature axes. In other words, spiciness would have different meanings for different (chosen) scaling factors.
* The meaning of spiciness changes with density. As a result, spiciness may only be useful over small vertical extensions in the surface layer. 
McDougall is adopted by the Intergovernmental Oceanographic Commission (IOC), International Association for the Physical Sciences of the Oceans (IAPSO) and the Scientific Committee on Oceanic Research (SCOR) due to their implementation of spiciness in the TEOS-10.
Huang claims that the orthogonal system is superior to the non orthogonal system because the coordinates can be regarded as independent and distances between points can be calculated more easily.
McDougall recommended that the spiciness should not be used. Instead, they recommend that the variation of salinity should be used to differentiate between isopycnal water parcels and the stability ratio  on vertical water columns for stability.