For example, the hotness can be 0 or the highest currently is around 5.700. Some hair styles also carry hotness and do add to overall hotness.
Also, if an outfit for a beach party is applied in an another party, the hotness will decrease or be equal to 0 in some cases.
Generally, the higher the level, the greater the hotness of items in a particular store. Thus, the top level stores carry the hottest items possible.