I was a builder for 30+ years and I know firsthand that all builders are not good builders. That is not to say the bad builders are crooks. It is to say that some builders are poor businessmen, have inadequate construction knowledge and know absolutely nothing about good design resulting in a product that is far from what the customer deserves.
The best way to check out a builder is to talk to customers that have lived in one of his homes for several years, customers that have lived in his homes for say 1 or 2 years and one that has just moved in. Ask them how quickly issues were resolved, ask if issues were resolved to the customer’s satisfaction and how many issues were never resolved? Talk to the trades working on his current homes, but do so when the trade is in the street or away from the subdivision. Do not approach the trade while he is working on the house. If a trade is disgruntled or has not been paid he will be quick to talk about the builder’s shortcomings.
Talk to the building inspector. He typically will not recommend a builder for obvious reasons, but if you give him the names of say three builders you are considering, he might give you a subtle hint as to which ones to avoid.
If a builder has uncompleted homes that looks as if there has been no activity for a while (weeds in the yard, weathered exposed wood etc.) look for another builder. Builders only get paid by the bank as they complete a phase of the work, so all good builders want to keep cash coming in. If work has stopped on a house, 90% of the time it is the builder’s fault. If the building site is a mess, it is a reflection of his respect for his customers.