Actually, I don't smell one. I hear one.
There are rats in our basement again. And they come up in the walls and get into the space beneath our kitchen cabinets - the space called the toe-kick.
They're bold as brass, too. Tonight, while I write, one of them is under there, chewing on something, crunching away. I can hear him. I walk over to the kitchen cabinets, quietly, and listen to the one he's under. Then I slam the cabinet door, loudly.
The crunching stops. But only for a few seconds or so. Then it starts up. You can almost sense the rat going - "Yeah? So what. Try and stop me."
We powered up the RatZapper again this evening. We no longer have a dog, so instead of dry dogfood, we used a handful of Corn Chex for bait. We positioned it along a wall - they tell you to do that, because rats like to run alongside walls.
Rat infestations are an inevitable part of living in a rural area. We get them at certain times of year. We zap maybe a dozen rats each summer.
Chew on this, you little hairy bastard!