Which is still smart enough to fool Harry.
Mister is not an average cat, he has managed to outthink one of the most dangerous wizards on the planet and a Foo dog. That make him slightly smarter than the average cat.
Just look at Fenris and Jim, Fenris is a slightly smarter than average cat, and rules that household. If the pandemic ends, and Jim tries to carry out his oft repeated threat of “out with the bears”, the obvious outcome will be Jim locked outside with advancing bears whilst Fenris looks on from inside the house with Bru and the other cats, and Jim wondering “How did that happen?”
Don’t try to do it Jim.