Dogs end up in rescue centres for many reasons.
It can often be because people haven't researched the breeds and don't really understand their needs. Also dogs like staffies are ten a penny and therefore cheap. They still, sadly, attract the wrong type of owner, just like huskies etc.
I love staffies, i wouldn't have one with a young child as they are really strong and heavy and quite frankly, mental :) An older child would make a great best friend for a staffie.
Husky - well, they aren't really designed (for want of a better word) to be pets unless the owner is prepared to meet their specialised needs but of course they are stunning looking dogs that sadly for them, look a lot like wolves and this attracts the wrong sort of owner.
Small yappy Jack russels, well i have one laying on my lap just now, quiet as a church mouse, it wont last! he will hear a pin drop somewhere and be off!! bark bark bark bark bark.
Jack russels (unless its a parsons) are not pedigree dogs so cheap and easy to come by. They are bought as family pets because of their size but this is decieving, they are high energy, stupid (or maybe too clever!) and difficult to train and have a high prey drive. My two are bastards (but i love them).
Chihuahuas, because they are sold as a fucking fashion accessory and they are dogs not toys, they can be nervy and snappy and people can't cope with that when all they want is to carry them around Harvey Nicks a la paris hilton. This boils my piss! Chihuahuas are great, feisty and all dog, they do not want to wear a fucking tutu and be carried around in a designer handbag!
You don't sound like you have that much dog experience but thats ok, you are doing your research which is good. I would recommend visiting some reputable dog rescues, a good rescue will be able to match you up to the right dog for you. Like you say, you could be taking on a whole bunch of trouble (i did with a rescue rottie, to be fair i was told he was a nutter, just not how much! and i have lots of experience) but not all dogs in rescues are there because their owners have been bad to them, they have been hard to train etc. Sadly more and more people are losing their homes and often have to give up their dogs, older people become sick and can no longer take care of them, people lose jobs etc. I actually think you have more chance with a rescue as an inexperienced owner than a puppy. I have two JRTs, one from a pup the other from a rescue, honestly, id never have another dog from a puppy again, can't be doing with toilet training etc, rescues often have other issues but the basics are there.
Good luck xx