Even a seasoned professional can be fooled. More than once, I've gone running for my tape measure, convinced that the framer made a mistake, only to find that all was as it should be. When the house is sheathed and the drywall put up, the rooms seem to grow and they begin to look as you had hoped they would. The outside remains massive, though, and will usually stay that way until the siding and roofing are applied. It isn't just the size of everything that's a problem.
Strange things happen to colors and patterns, too.
I had a client insist that I cancel my meetings and come to her home immediately to inspect the color of the paint that had just been applied to her living room walls. The newly applied paint looked nothing like the paint chip and she didn't want to let the painter continue applying the wrong color. It took a lot of talking to convince her that the color of wet paint is far different than the color of dry paint and that her walls really would look like the paint chip in just a few hours. Patterns that appear so prominent on a small sample can disappear like magic on a large piece of material. They needn't bother.