Jeff Atwood made a good argument against using "meta tags", those tags that describe things other than the content of the question. A tag that doesn't really apply to the content isn't very valuable for filtering questions, because they could be added to questions about almost any topic, and only add noise to the system.
For example, look at
[beginner]. This could be added to a question like
"How do i take a picture?"
and also to a question like
"I am branching out from portrait and wedding photography into fashion photography, what differences should I expect?"
Both questions would relate to a "beginner", but are about completely different topics.
[beginner] tags should probably not be used. What other tags should we avoid using?