I disagree with this. Knowing the breeder and that person's birds: what they have been breeding for, what they cull for, how long they have been breeding are some of the things to ask; photos of their stock can help. Seeing in person or at shows is better. Good birds of a certain breed you are looking for will only be found locally if you are lucky. A few hours to 1/2 a day drive to get good stock is worthwhile. Otherwise shipping from a good breeder is not a throw of the dice if you know the breeder and his or her birds.
What is important to know is, not all chicks, even from the best of lines, are going to be worthy of keeping. Most breeders will tell you 10% of a hatch, rule of thumb, are worth keeping. That number will go up or down depending on the line. With Marans, I would say that number is down. Way down.