Well, glad to see I'm not alone. I did a post about my Analytics problems just recently: viewtopic.php?f=1&t=88899
If you go to Map Overlay, then click on each location that seems to have an unreasonably high number of visits, an average of 1 page/visit, and an Avg. Time on Site of 00:00:00 for all of those visits, I'm pretty sure those are robots. (If you take it all the way down to City Detail level, and set the Dimension to Landing Page, you'll probably see nearly every page in your archive visited once, each page counted as a separate visit, from the same location—obviously, all the same visitor). Subtract that number of visits from your total unique visitors, and that should give you your actual number of unique visitors.
Because of the robots, my reported total unique visitors bounces all over the place from day to day--but I find that if I subtract those robots from my total, then I average a pretty consistent number of unique visitors from one day to the next.
I think even that number may not be accurate, because Analytics apparently misses a lot of short visits, so the real number may be higher than that. In fact, I'm almost certain it's low, because I was getting numbers like this from the old ComicGenesis tracker back in February, and it should have gotten higher than that since then. As I said in my other post, I wish I could find a stat tracker without these problems, but right now, I guess this is what I've got.