Yup, I think MAXXxxx has it right. While voting patterns change over the years (for example, seems a lot harder to get 50+ votes unless you make it into the top last 7 days or new and notable but I don't believe that was always the case), this still looks like a high number of non-registered to registered votes. Looking at my own pieces, most of them have around 50% of the votes as registered. Anyway, as MAXXxxx pointed out, if you advertise on Facebook and other forums, that tends to increase the number of votes and also inflate the score. If you take a decent figure (one scoring an 8 for example) and then ask for votes on a gaming forum, there's a good chance it will get a lot of 10's because they're used to a different standard.
As for what's the right score for this one... hard to say. The small pictures make it hard to really judge the painting quality. In addition, the standard for what's a 9 or 10 has increased over time. So back in 2011 this may well have deserved a score like that.
The gallery score and artist rankings on this site are more like general measures rather than precise ones. You'll get pieces that seem to be scoring a bit too high or a bit too low for bizarre reasons. And, in terms of rankings, I can pick out quite a few people who are ranked behind me but are definitely better painters than I am. I don't care what the ranking says, if I go up against Skelette, Megazord, or Jessica Rich in a live competition I fully expect to lose. That being said, you aren't going to find many (or perhaps any) people ranked in the top 100 who should ranked 500+. And, while you'll get the occasional piece that should be scoring a 6 but is somehow scoring a 9.5, there's not a lot of people actively trying to cheat the system. So if something is a 9.5 but probably should be a 8.7, it's most likely that they've got a bunch of friendly votes or happened to pick a subject that connects with people.