I find benefit in tagging appropriately to reach the right experts for the question. I don't think this is a debate in anyone's mind.
Let's say, however, that someone follows the java tag. What kinds of questions would they expect to see?
- Questions about testing Java programs
- Questions about testing using a Java framework (JUnit) (This will usually fall under the first one as well, but doesn't necessarily need to.)
- Questions about testing using a Java binding for a generic framework (Selenium's Java binding)
For me, I would follow it for testing Java programs. But, I think it would be more popular to see it for one of the other two. I would think any of those reasons (and probably others too) would be fine for tagging a question with Java. It would also seem like that someone following the java tag for a question about Selenium's Java binding would also be likely to be willing and able to answer ones on JUnit.