Imagine I have a house cleaner that comes in once a week to clean the house. After a while I start to notice that my house smells "fishy", but my house cleaner has just the ticket -- the all-new FishBeGone (TM) cleaner & fragrance that gets rid of fishy smells for up to seven days at a stretch! Sign me up, this fish smell is unbearable!
After a while I hear a rumour that FishBeGone is actually paying house cleaners to store rotten fish in their customer's houses, thus driving demand for the cleaner and ensuring high profits. I also hear that the most common place that the rotten fish is stored is under the central heating unit, thus providing ideal environmental conditions for dispersing the delicious, summery smell of hot rotting fish throughout the house.
Aghast that such a thing could happen, I quickly run out and buy a product that consists of a video camera and fish-smell detection unit. I install it in my laundry (where the central heating unit is) and sure enough, on the next visit from my cleaner I notice that he adds some more rotting fish to the ever-growing pile. I confront him with the evidence, fire him, and get the laundry completely cleaned up. So far, so good!
Now, I still need a house cleaner so I decide to contract one from a completely different agency -- one that has no known affiliation with FishBeGone whatsoever. And just to be sure, I keep the FishBeGoneBeGone system up and running for a few weeks but it never detects my new cleaner putting dead fish in my laundry.
But after a few weeks, I start to detect that oh-so-sweet smell of rotting fish carcasses, and sure enough my new cleaner recommends that I purchase FishBeGone to get rid of the smell. Worried that maybe this new agency wasn't so up-front as I first thought, I fire up the trusty FishBeGoneBeGone system for a few weeks and check the records, but they're all totally clean.
Maybe I just have a "fishy smell" problem in my house after all?
Or maybe the new cleaning lady was just putting the rotting fish under my bed instead.