Do NOT view a puppy until you know already it is not a puppy farm. Saying 'no' to a theoretical puppy you have not seen is vastly easier than saying 'no' to one snuggled in your lap. It will be almost impossible not to buy a puppy you have met, even if you know it is a farm.
Seeing puppies at a week old would be a flag for me. It is a big health risk to the puppy - having strangers handle it at such a young age with an immature immune system. Besides, what can you tell from a week old puppy? Nothing. It'll look like every other 1 week old puppy. It will have no personality that you can tell, will not be able to interact with you.
Depending on their story, you should be able to find online evidence to back it up anything a breeder tells you about themselves. As an example, my breeder (springer) was also a breed judge - I could find several mentions of her on various dog websites as being such, so I knew that was true.
She had bred 5 litters previously. I could verify this by looking up the dogs on the KC website. Her mum had bred before. I could verify this also. I could find pictures of some of those litters and the kinds of homes they went to (e.g. one trained as a deaf assistance dog).
I could check the bitch's health (DNA) checks online and see photos of her in shows. That meant I could eventually match those photos to the dog I met.
I could do the same for the father and also see proof he had been shown in various competitions just as she said.
All of this was from websites other than hers. In short, I could independently verify pretty much everything she told me. I did all this before meeting any puppy and much of it before there even was a puppy (i.e. before pregnancy).
When I did meet the puppies they were 3.5 weeks old and she spent 2 hours talking to me about how I planned to raise and care for the dog. She quizzed me on why I wanted a puppy and why this breed especially. She asked about my experience with dogs. She asked what Battendog's typical day was going to be and what my emergency/back-up plans were if the day didn't go to plan (e.g. if I suddenly had to go into hospital).
She answered all my questions on her dogs, why she bred, any previous health or behavioural problems, how and why she chose to breed her bitch to that specific dog. All answers were informative, considered and filled with genuine care for the welfare of the breed and her dogs.
She could give good answers on the care the puppies received, including what experiences they would be exposed to before going to new homes: baths, hoovers, washine machines, travelling in the car, children, other dogs, adults, handling, being separated from their litter and mum, being left alone in a room for short periods, being indoors, being outdoors.
I met the mum and could see proof she had recently been feeding puppies. I could see her interacting with those puppies and see her reaction when I interacted with them. I received the contact details for the father's owner so I could check with them and arrange a visit to meet him, if I wanted.
She invited me to visit the puppies again before picking mine up. She encouraged me to think about it carefully and not rush into saying yes/giving her a deposit.
I could see a draft puppy sale contract. It included clauses that I would return the dog to her, at any point in its life, if I had to rehome him. She talked about the lifetime support she gave - any problem with the dog for any reason, and I could call her to talk it through.
There may be slight variations on this theme (e.g. working dog breeders won't have show history etc) but the fundamentals should be the same.