stealth hottie
The girl or (guy) who either deliberately or unknowingly downplays their hotness to appear less attractive than they really are leading people to not recognize how attractive they are in social situations. Some keen observers could notice this ruse and see that they are a hottie even when they are in stealth mode.
Damn, I think Ally is a total stealth hottie, she may wear loose fitting clothes and sweatpants, but she is totally hot if and when she is made up.