I have seen several tag Wiki edits in the edit queue that are very enthusiastic in tone bordering advertising, and usually don't add real value to the Wiki.
A random example that I just saw in the queue (relatively harmless compared to others I've seen, but I didn't write those down, and I'm too lazy to do the research right now): WordPress
Now this is well-intentioned, and not really harmful as such. Maybe I'm being too harsh altogether, but I'm not thrilled about project-and product-related tag wikis becoming a billboard for fans. I would like to see some Wikipedia-Style neutrality here.
Are there any guidelines for this? All I can see on Meta is more general stuff like this list of tips.