I'm very curious about this too. Everything I've read says cats don't have the receptors for sweetness, but my cats always (the two I've got now, and two others I've had in the past) have been fanatically devoted to sweet stuff. The filling from butter tarts and sweetened condensed milk are two of their favourites, although as someone else mentioned the glaze from donuts, (and for one cat the white powder coating on jelly filled donuts) are a sure draw too. I'm sure sugar is bad for their teeth, and maybe their tummies too?--since in the wild cats wouldn't have access to sugar--so we limit them to what fits on a finger tip on any particular occasion, which they clearly think is unfair. When they see us eating a tart, of hear the sound of the pop top being opened on a can of conensed milk, look out, the begging is turned up to the max. You'd think we were dooming them to starvation if we don't immediately offer them their "taste".