Some people have been talking about the idea that these tag things are too loosely constructed, and non-expert, and therefore may not serve any sort of useful, official purpose in terms of making the content they describe easily retrievable by anyone when the volume gets really big.
These questions have been raised as ones of ‘accuracy’ but they’re not. They’re about perspective and culture. Accuracy is only meaningful if we share the same cultural assumptions. Ironically, we know that culture matters at some level, if only via our collective choice to discuss FOLKsonomy and ETHNOclassification.

Given that we’re dealing with culture and structure, we must also think through issues of legitimacy and power. How are our collective choices enforcing hegemonic uses of language that may marginalize?
- danah boyd

That's just what I was thinking! Minus words like hegemonic of course, and I wasn't too concerned about marginalisation just yet.

As I was tooling around seeing what people were writing about tags, culture, experts, evil design, transparent design, information ecologies and such, I came across a slightly left-field, and yet strangely relevant discussion on a site called 6109: 2k4 about "tag-bombing" in South London (with spray paint in a public place).

"back to tagging, it really is crap. Was on a packed train once and three "kids" got out thier markers and bombed and the whole place. Literally packed in like sardines and they had thier arms stretched up tagging the roof/doors etc. No one said a word....."
- detective boy, 24.12.2003

"I also feel righteous as a south london resident doing this. Because although the billboard spaces will be owned by local people. Ultimately, it's people living in glass penthouses who commision this bollocks, and they dont have to see the interior of some wanky advertising juniors brain everynight when the trudge back from work, or the pub."
- Mrs. Magpie, 06.01.2004

"Some lads near where I live took the whole tagging thing too far when one of them stabbed and killed the other one for crossing out his tags......"
- Giles, 09.01.2004

"i reckon that the taggers add a beautiful and dynamic texture to our environment & you won't get much graffers doing big pieces who didn't start out as taggers, not to mention all the social bits about underpriv yoof etc..."
- Ol Nick, 09.01.2004

The tapestry is so rich I can almost smell it. None of us really know how to clean it either.