Ruggysgirl- You are falling into the logical mistake of the syllogism. 1) Guiness is good beer. 2) The cat has his head in an empty Guiness pint glass. 3)Therefore, the cat knows good beer.
Just because someone stole a pint glass from the local tavern...does not mean the cat knows good beer. For all we know, this cat may have a prediliction for its owner's Milwaukee's Best, typically consumed each nite in the pilfered pint.