Back in the 70's I remember seeing one once while quail hunting with my Dad. I was new to hunting then & we were both new to hunting in the Arizona desert. After describing the critter to Dad - told him it looked like a racoon crossed with an otter - he accused me of carrying something other than water in my canteen. Took a trip to the school library (the internet wasn't even a bad thought back then) to show him confermation of what I saw.
From what I've gathered over the years, seeing one seems like seeing a bobcat - not too likely unless your specifically going after one. I remember talking to a Air Force Lt (I was an Air Force brat living on base) who did alot of varmint hunting & said that he'd called in a few of them. It would make an interesting mount if you got one though.
I have only ran into a couple in all the years that I have been hunting in the desert of Arizona. That time all I had to shoot it was a .44 magnum loaded with 240 gr hollow points. I really didn't want to blow in into pieces so I let them wander off never to see another one since.
When I first learned of them I thought there were a lot more than there is. I think they are more of a night animal like a racoon though so that could be some of the problem. A .44 would definately be overkill. I was thinking more like my .17hmr but doubt I will ever get the chance at one.
From the books that I have read, there is a lot of importance in knowing every nook and cranny of your hunting territory as well as the animal that you are hunting. So scouting as much as possible, just walking the land, will give you a good idea of what's around the corner or what's on the other side of a hill. Which can be very beneficial.
Making your own maps of human and deer trails, and different types of foliage such as group of pines,...