Now if you'd paid any attention before talking to a Sim, you'd notice that you can give cakes as a present to a Sim. I figured out which cakes to give to what Sim, so here goes. The cakes you give are based on the colors a Sim wears. It's mostly based on their hair color and pants/shorts/skirts. Never go by the eyes, skin color, shirts, or shoes as they don't work out. Even if a certain Sim were to wear a lot of one color, don't go by that but rather the small details. For example, if there's any colored lining, stripes, or buttons/buckles on their jeans.
Shortcakes are good with anyone wearing red or pink.
Cheesecakes go with anyone wearing yellow.
Chocolate cakes are for Sims who wear brown.
Mont Blancs are for those who have black, silver/gray, and/or wear white on themselves. Mont Blancs are also good when a Sim wheres a lot of blue.
Chinese cakes are a risk, as if you give them to a Sim that doesn't like them, they instantly get angry at you.
If a Sim doesn't wear any of those above mentioned colors, I recommend giving them a lei, bouquet of flowers, or nothing. It's good to a lei or bouquet give any Sim wearing flower prints on their clothes as you don't want to waste your cakes either! =D