Seriously great you are adopting
Yes, if they are chewing on themselves, like their fur, it is not good, so hopefully that's not what you meant. But if that is what you meant, than I would still adopt him cause it's a stress issue (I believe always, but I could easily be wrong) and caused by something in it's current environment, so once it goes to a more calm, stable, comfortable environment, chewing on his fur should stop.
If you mean people, I believe you can teach them not to bite. When my boy, Sunny, does it, I say no in a quiet, yet strict voice, and it gets his attention. He immediatly stops. But he only does taste-test bites that don't hurt. He just wants to know if things are edible and/or chewable, like my shirt. Warning bites are when I say "NO" and he does stop. That's when I may doing something he doesn't like, like the past few days i've had to force feed him meds and Critical Care cause he had a Urinary Track Infection, so he's done a few warning bites, which are a little harder than his taste-test bites-they feel like a pinch, not enough to draw blood (he could draw bloood if he wanted to), but the real bite would be the next step, so I don't let him get there.
If you mean he chews in general, like the furniture, his cage, and whatever else he can get his teeth into besides flesh and himself, then that is 100% normal for chins, so expect it from any chin you get. Sunny eats his cage (the wood, not wire cloth), his hidey house (wood), and when he's oout of his cage, he used to eat the baseboards so I've covered them up with cardboard. He would eat any furniture as well if I'd let him. Somee chins even eat fleece-Sunny doesn't, but he nibbles on aspen shavings often to I'm switching to fleece. They sshould have lots of applewood and other safe wood to chew on in and out of their cage, and also pumice is great for their teeth. Sunny loves his pumice ledges and his teeth are very heallthy. He also loves tearing apart a small roll-a-nest when he has one or a grass hut, but he tends to pee on them, not the roll-a-nests. And of course hay, which takes care of wearing their back teeth so its very important. Sunny gets Orchard Grass and of course Timothy Hay, but there are other kinds that are good, like Oat hay. Just stay away from alfalfa, especially if you use Mazuri pellets.
And I don't think a crooked tail would effect holding the chin by thhe tail (not just the tail of course), but there are other ways. It's hard to describe, though, so I'll leave that up to the more experienced members. I could also be wrong, and maybe you should stay away from the tail all together. If it effected anything, it would probably affect their balance though, because they use their tails when standing on 2 feet, like a kangaroo (not as a weopon though, lol).
After getting a chin, though, especially one that has an abnormal chewing problem or a crooked tail, I'd bring them to the vet right away after bringing them home-a vet that KNOWS about chins. I had to call a few different vets and one actually said to me that they've treated sugar gliders and guinea pigs, so why not chinchillas, too?! Something like that is not good enough-definitely not-that actually got me a little mad, especially since that's where I take my dogs. I finally called the emergency animal vet 1/2 hour from me, they said NO, just a blunt no, the first definite answer I got, and gave me the number to another vet near them who said YES, a ddefinite answer, and when I brought Sunny in, they did a very good job and they said his meds were right on here-I trust a lot of the members on here more than any vet for my chin, so now I trust Sunny's vet more because the meds and food supplement were good (according to some members on here), and he's already doing a lot better. If you don't feel comfortable with the answer of whether or not they KNOW about chins, look else where, and even after finding a vet you feel comfortable with, if they prescribe anything, ask about it on here, and if they give advice that doesn't seem right to you, ask about it on here. You can trust the people on here-some have over 50-200 chins and have owned and/or bred for many years, going through almost anything you can possibly go through with a chin! And you should take a rescue chin to the vet immediatly in my opinion, especially off of Craigslist, just to make sure everything is good-that's just my opinion, though-I would.
Good luck with the chin you choose. Either 'problem' doesn't SOUND like a serious one, but again, others may have different opinions.
