Years ago my husband and I took leave of our senses and opted to install new wall-to-wall carpeting in our home, despite the fact that, A, we hate carpeting and, B, the job involved a two-flight circular floating stairway that dominated the house.

But since we couldn’t afford wood floors and the existing carpeting was trashed, we crossed our fingers and hoped for the best. (As it turned out, while they certainly have their place, hope and prayer are of little value during most home renovations.)

Foolishly we went to one of those “Carpet Giants” who offer the lowest price and the quickest turnaround, unaware that they were the most likely to employ cheap labor, i.e., inexperienced workers.

This is no small problem; in fact, it’s potentially the biggest. Years earlier, on a much smaller job involving just one room, the carpet installers were due at 9 but came at 4, worked until 3 in the morning and left a mess. So we were thrilled this time when the crew came at the appointed hour, worked efficiently and left everything spotless. What could possibly go wrong?

Distracted by my young son and with my husband out of town, I signed off on the finished job despite wondering if it was the setting sun making the carpet in one half of the living room look darker than in the other. The next day my husband, a.k.a. Old Eagle Eye, returned and almost had a stroke: He was sure that the carpeting was darker on one side of the room than the other, and the stair treads appeared darker and lighter at random.

How did it happen? The awful truth was that the installers had goofed, big time, when they pieced the carpet together. Turns out that the direction of the pile affects the appearance of most carpeting. Try it: rub your hand one way over your carpet, then the other way, and you’ll see how the color changes.

Several angry-lawyer letters later, the formerly friendly salesman grudgingly agreed to redo the job at no charge. Lessons learned:

1. Never doubt your instincts. If something doesn't look right, even if you can't put your finger on it, register your reservations and don't sign off until you’re satisfied. Take time to get a second or even a third opinion. Don’t be a jerk, but if something doesn't feel right, it’s probably wrong.

2. Pay attention to the people who will actually be doing the work. The congenial salesman in the showroom who was trying to get your business may have been a great guy, but on the Big Day you’ll want workers who arrive on time, do the job well, and respect your home by cleaning up after themselves.