I'm not familiar with that scale in particular, but I would say she was an 8 or 9 by most standard measures. That was actually running through my head as she approached, which maybe explains my hare-brained response (but probably doesn't).
10: Almost flawless and very rare. Could be a top model, top playboy centerfold (nationally amazing, the MENSA of hotness)
9: The hottest girl at the club, The hottest girl at school, etc (more locally amazing)
8: One of the hotter women at the club, one of the hotter girls at school (upper class of hot women)
7: Cute girl at the club, in classes, at work, in apt building. Definitely cute, but not tops locally.
6: Fairly attractive, no major flaws but maybe minor ones
5: Starting to be unattractive, but certain qualities work in her favor. Nothing major, but minor problems are more common
4: Not attractive. Major flaws start piling up (overweight, blemishes, etc.)
3: One of the uglier girls in school, one of the uglier girls at work (lower class of ugly women)
2: The ugliest girl in school, the ugliest girl at work (couldn't even get into a club)
1: Absolutely disgusting and hard to look at. Young children point and adults look away upon seeing (not one single redeeming quality)