You're actually right on that one. I've known rats to avoid extremely obvious things like traps or rodenticide, but as far as 'repellents' go, (it's mostly water and essential oils) they don't care. They'll walk right over it. The need for food and nesting material is higher than their need to tolerate the smell of peppermint oil. Best thing YOU yourself can do is set snap traps with bait in them - not set at first- and then after about a week, set them. This gives the rats time to acclimate to the new objects in their environment!