Just the other day in my office, I was floored to hear one of the agents talking about an incident during a final walk-thru at a new subdivision in our area.
It seems that all during their inspection, the buyer kept hearing a faint mewling sound, but couldn't identify where it was coming from. Fearing it was a kitten trapped on the roof or lost somewhere outside, she spent an hour looking everywhere for the poor little thing: nothing. zip. nada.
Frustrated, she went back inside to see if it could be spotted on the roof from the 2nd floor. No kitty. Almost ready to give up, she noticed the sound was a little bit louder in the living room, but there was no beastie to be found! On a whim, she rapped on the wall, only to have the mewling get louder: the kitten was stuck in the wall somehow!
After talking to the site agent, she tired of waiting for one of the construction team to come over and borrowed a crowbar from a neighbor and punched a hole in the drywall--out came a full-grown adult cat, plenty upset at being sealed up in the wall for who knows how long! If they hadn't done the inspection...who knows what could have happened by the time anyone knew. Probably a home inspection during the construction process by an outside, licensed inspector could have found this during or right after the drywall phase.
Moral of the story--walk thrus aren't a formality--they can save lives!