For each type of resource you have connected to your cities, it causes a certain number of smilies. Redundant resources (2, 3, 4 or more of dye) connected doesn't add to your smiley pile, but having more of EACH type does.
For example, if you have dye and silks connected to a city, each of these resources gives you one smiley. If you have, say, 2 of dye and 3 of silk, you still only get ONE smiley per resource. [however, you can trade these extra resources to other civs].
After the first two resources, though, the number of smileys increases for each added resource- add, say, furs to the list, and now you get FOUR smileys (one each for dye and silks, but two for furs), and so one until you get all of the luxury resources.
However, the neat little catch Firaxis to this is: you only get one smiley for resource, no matter how many you have, until you build a marketplace in that particular city
