First of all, the Nogtail is incredibly fast and hard to catch. It is also said that it brings the Blight, which is a disease that can kill and harm plants, which could be rather dangerous as the Nogtail usually would find itself living on farms. It is also said that the Nogtail might help in recreation, even though the understanding of this subject is little and not much is known about it.
Nogtails would indeed be an interesting pet. Firstly, I would hardly recommend this creature as a pet for anyone holding plants or wishing to hold plant, due to the sickness it bears. But, if you are not one of those, it might be an okay animal for you. It is believed that it eats the same as pigs and otherwise act much like pigs, meaning that you should have the time and abilities to care for it - and that it might get a bit smelly. The creature is also deemed XXX, meaning that you should definitely know a bit about this creature before deciding to live with it. Otherwise, I do think this creature can hold as an alright pet for a person who does not require a pet who is around them all the time, and does not like a cuddly pet - even though I am sure you could train it to cuddle you!