When dealing with guitars, few topics are more controversial than sound quality. Skilled players and experienced listeners generally agree on subjective rankings of instruments, but the differences are notoriously difficult to measure and to describe using objective metrics.
Perhaps the fundamental problem is that descriptions of the sound of an instrument are almost universally imprecise. It is common for a guitar to be described as ‘bright’ or ‘smooth’ . One particularly good sounding guitar that was louder than expected was described to me by an expert as ‘a cannon’. The people offering these descriptive terms are clearly trying to find words whose emotional connotations are appropriate to his or her reaction to the sound. This type of allusion is the cornerstone of literature and poetry, but offers very little useful information to the analyst or the designer.