You know - it's different for every person. Whether you like black in comparison to white, contemporary in relation to traditional, tall to short or elaborate versus simplicity. But when you take orders for cakes on a daily basis you start to notice small comparisons.
A couple will all call for a super hero cake or a Batman cake...
Some of them require research - I jump on the 'net and find photos of related items. For the Eiffel tower, I printed photos of the front, side and top views.
For the 'Companion Cube', I looked into the game. I wanted to write "the cake is fake" on the board because I thought the idea of placing a placebo cake with real recipe into a game was brilliant. The client didn't think so. When my partner brought it up with her son upon pick-up, the birthday boy exclaimed that it would have been 'the ultimate!'