>go look at 2-3 houses that they finished - you pick them, don't let them pick.
Does this work in practice? How can you "pick them" without the builder telling you which houses they built? Do you expect people living in the houses to let you wander around their homes looking for contractor flaws?
You ask them for the last X houses they've built and pick randomly. People are generally happy to do this: this proves to them their house is good enough for their contractor to show to others and most people don't move into a finished house right away anyway.
Does this work in practice? How can you "pick them" without the builder telling you which houses they built? Do you expect people living in the houses to let you wander around their homes looking for contractor flaws?