If this doesn't guarantee that you do your walk throughs, I don't know what will. 

A week ago I had a closing on a brand new home. The buyers had requested the seller switch out the white appliances with stainless, and this was done at noon the day before closing. The new owners had insured the home the week before closing, so that they could move all their things in. The wife was due 1 week after closing with their first child. All they had in their apartment was a blow up mattress and enough clothing for the week.

We arrived at 5pm to do the walk through. Since we are in a northern climate, the heat was on and running in the house. I opened the door and a strong smell of gas filled my nose (and no, I hadn't recently ate any Mexican food). The smell wasn't strong enough to make me think the place was going to explode, but I knew I had to get windows and doors open to air the place out. I asked the buyers to stay outside, and I proceeded to open all the windows on the 1st floor. I got back outside, called the builder, and told him to get someone out there asap. Luckily, my buyers were remaining calm.

The plumber arrived within 20 mins, and discovered that when the appliance people installed the new gas stove, they had cranked on the gas line with a wrench and broke open a union on the basement. This left a 1/2" gas line leaking in the basement only 15 ft from the running gas furnace and gas hot water heater. The plumber said that had we let it go until after closing, the house would have exploded. The gas would have been flowing into the house for 24hrs at that time, and would have filled the whole house to an extreme level.

Needless to say, My buyers would have lost everything they own. I can't imagine having my first kid and literally owning a car, an air mattress, and a few pairs of clothes. I will definitely do all walk throughs from now on!