It takes a lot to get my 10 vote. I think as the highest you can possibly vote a photo, the thing better be one of the top 50 photos on the site to get that vote. Otherwise, if everybody voted thousands of photos as "10's" there would be thousands of photos receiving the highest place and it would thus be useless to really find the best ones out of those really good ones.
Come on let's start a trend - vote inflation is causing a lot of amazing photos to get lost in the shuffle. There are TEN POSSIBLE VOTES - 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10. Here's how I suggest you use them:
Brian's SummitPost.org Voting Guide
10. Absolutely stunning, magazine quality, pro photographer or should be
9. Excellent but not quite a full page mag spread...
8. Great photo
7. Good photo
6. Lacking pretty majorly somehow
5. Really not a good photo at all
4. Why did you upload this thing?
3. Were you smoking crack when you uploaded this thing?
2. I'm angry at you
1. I HATE you