Makes you think, doesn't it?
When I treat mine, it tends to be with fresh meat or fish, along with the odd bit of ham and such like. Sometimes it is just as a treat (like with ham or a splash of milk) but if I do give meat or fish, it tends to replace a meal of their regular wet food rather than supplement it. For instance, last night, they both had a dollop of minced beef for their tea, which went down very nicely, thank you!
I think it's just about being sensible - and it's probably easier to be sensible with a cat as opposed to a dog. Dogs (and I must confess, humans) will eat just about anything and therein lies the problem... The odd treat is fine, but don't forget the exercise...
I've just scoffed a creme egg, so best get on my bike then!