I can only speak for my one litter I was co-breeder on. It was planned 2 years ahead of time, and there were 3 people who wanted pups, plus the other breeders and I would each take one, so there were 5 spoken for. The other 3 people were well known friends who were very familiar with Whippets. Both parents were checked out before breeding, and I did extensive research into the pedigrees looking for anything that could be a problem. Granted, not all problems are disclosed of course. Our breeding was a complete outcross, so while that can be better health wise, you can get a surprise like blue eyes....we didn't though.
In the litter we had 7, and as soon as the pictures hit the web, we had many inquiries, plus I had people referred to me by other friends/breeders. We did not want to have to advertise, so that is why we took the time to plan and gather interest. I don't see a problem with advertising a litter, if you plan to actually screen the people and get referrals. Craig's list...no way....a reputable news paper where you have to pay to take out an ad is much more acceptable.
The thing we also talked about in the planning stage was price. We felt that if anyone was going to get a pup that we didn't know that well, we would ask a higher price than then "friend price", just to be a little more assured the people were serious about getting the dog. Sadly, some people think of animals as property (well, legally they are!) but if they have to pay for it, they might treat it nicer
I drew up two contracts; one was for a performance home that did not require neuter/spay, and the other was a pet contract that did require neuter/spay (we specified also that males not to be neutered until 12 months and females 8 months). Also in the contract was that if the person for whatever reason could not keep the dog, it was to come back to us, or cleared with us if the person was going to put it with a family member.
Another line said that if the dog was bred, that no puppies could be sold to puppy mills or pet stores.
While these contracts can be hard enforce, they are legal contracts. The idea that breeders are very serious needs to be instilled into the buyers.
Thankfully, all of our pups are with people we know and are all active in racing or showing except for one who is a couch potato