Thing is, "sentiment" on stock boards doesn't really need to be tracked. Or it could be tracked simply by checking posting volume. It isn't hard to figure out.
On most stock boards, positive sentiment outweighs negative sentiment by about 9:1. The ratio may even be higher. That's because most posters are longs, want the stock to go up, and believe it will. Ten percent or fewer are critics, and almost no one listens to them.
Sentiment will only become extremely negative in response to certain events: if, for example, the company announces a reverse split, or, even worse, its stock is suspended by the SEC.
Positive sentiment may decline somewhat over time if the company just doesn't deliver, and stock price stagnates. But most longs will simply sell and leave, rather than switch to negative posting. When there's no real interest at all in the stock, sentiment is likely to stabilize in the slightly positive range. Some people never give up.
And that's about it...