The most common pests to affect houses & businesses are without a doubt rats & mice.
It isn't enough they bring germs & really nasty diseases they also bring with them a small army of ticks, fleas & mites.
Around the world these fur covered bringers of infection also account for an accumulated huge tonnage of spoiled, damaged and eated food and bring misery and death to many in less fortunate countries.
Rats & mice are supremely adapted to survive and, with the exception of the North & South Poles, have managed to collonise every corner of the globe with mice being behind only humans as the second most successful animal on the planet.
Squeezing through gaps as small as the size of a pencil it is very hard to keep mice at bay if your property is less than well maintained, especially if your property is connected to any other buildings. A good clue to mice living alongside you is the presence of many (usually black) droppings the size of a small grain of rice.
Rats however leave few if any droppings exposed to show signs of their moving in. Rats prefer to use latrines in out of the way places as a survival adaptation as, being a larger animal, they would be more likely to be discovered quickly.
These animals are constantly evolving with changes in their resitance to bait and baiting techniques happening quite quickly as they can breed every 3 weeks.
Most rat & mouse bait commonly bought by the public is unlikely to work. This is either due to low quality formulation or simply the rats & mice are impervious due to inbuilt resistance to either taking the bait or mutations in their DNA.
The main way to stop rats & mice is to block their entry and exclude them. Once they are in a property rodenticides and traps can be used. Sticky traps should never be used by non-professionals as these are inhumane.