Have you seen this rating pattern when you're looking for a product on some on-line store. I'm finding it more and more common, and I've been calling it the 'hook-em' pattern. After all, I do live in the Austin, Texas area and the well known finger pattern is universal around here. (Except for the Aggies.)
The rating split is usually because some subset of the raters are upset about something, usually having nothing to do with the quality of the product itself. People can give feedback in two ways on most systems, an actual text review, and a quick numerical score, so it's pretty easy to find what the hot-button is that's causing the trouble, and the artificially low scores. I suppose it could work the other way too, with a poor product with some people giving it high marks for good intentions or something, but I expect that's rare.
In practical terms, I tend to just ignore the one-star scores because they generally have nothing to do with what I'm interested in -- a feel for the quality of the product. What is dangerous are those systems that don't give you this kind of bar-chart look at the distribution of scores. In that case, the single number score can get seriously distorted, and mislead the shopper.
So cheers for the stores that give you more data.