Is cui os oleat an sanus sit quaesitum est: Trebatius ait non esse morbosum os alicui olere, veluti hircosum, strabonem: hoc enim ex illuvie oris accidere solere. Si tamen ex corporis vitio id accidit, veluti quod iecur, quod pulmo aut aliud quid similiter dolet, morbosus est.
(Ulpian, Digesta 18.104.22.168)
The question arose whether a slave who has a bad breath is sound. Trebatius says that a person whose breath smells is not diseased any more than one who smells like a goat, or who squints; for this may happen to anyone on account of a filthy mouth. But, however, where this occurs through some bodily defect, for example, from the liver or the lungs, or from any other similar cause, the slave is diseased. (tr. Samuel P. Scott)