Basically sweetness is a relatively new (first described by Radovich and Oliveros, 1998) attribute used in 3D seismic interpretation and visualisation is appropriately named ‘Sweetness’. This is due to its strong ability to visualize subtle channels and their internal structure in deep-water clastic and coastal plain settings.
As DKarlstadt points out it's meaning or quantative use is a difficult concept. But, it may be used in a semi-quantitative way to predict net-to-gross ratios in channel systems (Hart, 2008; two follow-up articles available). However, its units are difficult to understand and better thought of as relative values. This is due to Sweetness being calculated from the Instantaneous Amplitude divided by the square root of Instantaneous Frequency. This mathematical definition combines attribute relationships that are very useful for identification of isolated sand bodies in shale successions as they generate stronger broader reflectors than the surrounding shales. When seismic quality is bad, acoustic impedence contrasts between sands and shales are low or when they are highly interbedded the effectiveness of Sweetness diminishes.
that's my understanding of sweetness....