Unlike the Zubat, who make up for their blindness through echolocation, Deino are truly disabled by their blindness. These pokemon can only poorly perceive the world around them, for they lack eyesight and their senses of hearing and smell are insufficient to make up the difference. Yet Deino excel in their remarkable sense of taste, for a single bite allows them to discern not only an object's flavor, but also its size and shape, and in the case of living things, its most recent meal and travel pathway for the last hour.
Deino have short tongues, and their taste buds are also contained in their teeth, so they will bite as often as other pokemon sniff or stare. Although their trainers and teammates learn to adjust to this behavior, strangers among pokemon are not so understanding, and Deino are often found beaten up when they their victims inevitably take offense and fight back. Their bites, after all, are pokemon attacks – albeit ones they find necessary to see – and should Deino find the pokemon they bite to be a potential combat victory or a tasty morsel, they will not hesitate to follow it up with more.
Caretakers of these pokemon have quickly learned that Deino do not seek to devour them, and that their bites are simply a frustrating part of keeping these pokemon as pets. Most have struggled, however, to find any supplementary use for Deino, although sufficiently patient trainers will be satisfied with a Hydreigon's power. Some police departments have experimented with Deino, both for their taste-based searches and a sadistic appreciation for the prospect of having them bite criminals. And they have often been used as family guards, because even the criminals who know they are not man-eaters are loathe to take a bite from a charging Deino.