The level of stunning a person is when dressed up, usually based on positive contrast to daily appearance. A very good looking woman who dresses very nicely every day can have a low wow factor as there is no great contrast between how she looks for a special occasion and on a daily basis. A girl who normally dresses in a boyish or sloppy manner however will, when groomed, usually have a high wow factor because of the contrast to how she usually looks
The wow factor is often at play in teen movies where makeovers are involved.
"Did you see Miranda? They got her out of her baggy pants and combat boots and made her wear makeup, hot damn that's really the wow factor at work."