If you're thinking about buying a puppy from a breeder, then there are a few things to be aware of to make sure you buy safely, and that you get a happy, healthy pup, as well as making sure you aren't contributing to the disgusting puppy farming industry.
Puppy farms aren't always a literal farm as a lot of people would expect. They can be a normal house, and without a bit of knowledge you could easily end up buying a puppy from one without realising. It's hard to go and view a litter, and then turn around and say 'no', because of the environment they are in, or because you get an uneasy feeling about the place - if you are staring an adorable pup in the eye, how are you going to turn your back on him? So be prepared before you go - ask the right questions on the phone to the breeder, and know what you are looking for.
Firstly - you should be able to see the mother of the litter, and all the other litter mates, ideally the father too. If the breeder refuses to let you see mum or the siblings of your puppy - that's a red flag. Puppy farming means that a person keeps a bitch and breeds from her over and over again - often from a cage, but even if the bitch is kept 'comfortably' in a house, this is not OK. From a health perspective, bitches should only have 2 litters a year at absolute maximum - and the Kennel Club stipulate that they should only have a maximum of 4 litters in their lifetime. The sad fact is, puppy farms breed their bitches over and over again which is dangerous and cruel.
Puppies should be with their mothers for at least 8 weeks before separating them. A good breeder will often keep the pups for longer than this - up to 12 weeks, to make sure they are safe, healthy, and have learnt all they need to from their mum before leaving for a new home.
The mum should be over one year old, ideally over two, and no older than eight (depending on the breed). This is the Kennel Club ruling, but eight is fairly old for a bitch to be whelping.
Make sure the environment seems safe, clean and healthy. Ask where mum and puppies sleep (ask to see this when you arrive if it is not obvious), what food mum is on, and what food the breeder will start the puppies on. Stay away from the likes of Bakers, Wagg, Pedigree, or any pet food with additives, preservatives and sugars. Puppies should be on wet food to begin with, and then on puppy dry food mixed in until they are old enough for proper doggy food.
If you have a bad feeling try your very best to walk away, and contact the RSPCA if you feel it's necessary. Leaving a puppy behind in that situation is practically impossible, but if you pay for him then you are contributing to the trade, which fuels the evil 'breeders' to continue exploiting and torturing those poor mummies.
A puppy from a puppy farm can end up with any kind of health or behaviour problems, and of course leaving mum behind to have yet another litter.
I got Aslan from a wonderful family in Bournemouth, who had registered with the Kennel Club, but only had the one litter as they wanted his mum, Nala, to experience having pups, and they wanted to keep a puppy for themselves. I wasn't able to see his dad, as he lives in Birmingham, but they had done all the relevant tests with both mum and dad to ensure a low inbreeding percentage, meaning Aslan and his brothers and sisters should live a long, healthy life.
Make sure you research the breed you are looking at before buying - I can't stress this more. Find out how much exercise they need, how much grooming, whether they are a working breed or a 'family' breed. There is a wealth of information on the internet there for the taking - make sure you get the right best friend for you and your family.
Good luck to you if you're going for it - just keep your head on your shoulders and don't go and see a litter if they don't sound right on the phone. If you're ever unsure, contact the RSPCA - if the breeder is legitimate then it won't do any harm, but you may help shut a puppy farming operation down if your gut feeling was right.