It really depends on the time of day, month, year.. a lot of factors go into it. This morning I did my hair and makeup and I was like "you know what? I could go head to head with Beyonce on America's Next Top Model", but 2 weeks ago I rolled out of bed and was like "eww.. I look sick. I'm so ugly" I mean everybody has their days.
I'd say on average I'm a 7/10, when I actually try and put in the effort (which is rare, but it does happen) I can be a 9 and I break the necks of both guys and girls while they're doing double takes and I walk down the street, but I mean that's after spending like 2 hours on my hair and makeup. Can't do that everyday. If I could I'd be living like Kim Kardashian. On my worst days I am more of a 3. Just bleh
It ranges from "I could see why some people like you" to "holy crap I can't believe that's my face! How long have I been like this? How long has no one yet told me that I'm a rare beast of hideousness that should never resurface for fear that I might disturb the kind normal people." Depends. But usually I'd say its "hmm...mirrors are weird."
I guess because of the many compliments I get, I do assume that I am good looking when I look at myself in the mirror. But I suppose I consider myself more average because I see Lots of pretty girls around, and I'm sure many are much prettier than me. But I like how I look like and wouldn't change it for anyone. Interesting question! :)