Final answer:
Dry, crumbly pastry dough often indicates it has been overmixed or contains too much flour, which affects the texture by either developing gluten excessively or absorbing too much moisture.
Step-by-step explanation:
When pastry produces a dry, crumbly dough, this often suggests that it has been either overmixed or contains too much flour. Overmixing the dough develops the gluten too much, leading to a tough dough, while too much flour can absorb the moisture needed to bind the dough together, resulting in a dry and crumbly texture. However, it generally does not indicate too much water, as excess water typically leads to a stickier dough rather than a crumbly one. Undermixing, on the other hand, would likely lead to a dough with uneven moisture and fat distribution, which can cause issues but not typically dryness and crumbliness.