Blocking web analytics solutions?

Adam asked this very interesting question on the Yahoo! Web Analytics forum: "I have a client that claims that visitors are able to block all of the Omniture tags on their site. Is this possible? I'm not referring to cookies, rather the entire functionality. Has anyone else ever heard of this? If so, how can a visitor do this or what apps can cause the Omniture tags from firing off."

I see many ways this could be done with various levels of efficiency, and this is true of any tag-based solution, be it web analytics, ad networks or even widgets such as Feedburner subscribers count and many others. Some people have already highlighted a couple of ways. Here's some more info:

• Disabling Javascript: mostly unrealistic, this would render the web almost unusable. I don't believe a large portion of users would do that, other than privacy idealists who would pay everything cash to avoid being tracked by credit card companies...
• Disabling 3rd party cookie: obvious and easy, and that's why it's so important to use 1st party cookies, or at least what is called "friendly 3rd party cookies"!
  
• Antivirus/antispyware/ad blockers: also obvious and mostly the same thing as disabling 3rd party cookies because those tools will look at the 2o7.net used by Omniture (or whatever tool)... again, use 1st party cookies!
• Special browser extensions: most of them use simple URL and cookie detection... again, use 1st party cookie. More advanced ones might look at the presence of a specific Javascript object and substitute the function by a stub one... This is probably the most effective and advanced way of doing it. Doing this with Greasemonkey would be very easy.
  

Which brings an interesting point... while developing WASP I thought about adding an option to block specific tags/solutions. In some cases it would make sense for WA analysts and for implementation quality assurance. I decided not to do it because this would have made WASP the best anti-web-analytics tool on the market! I think education is better than this!

But then again, although 3rd party cookie blocking is easy, it's still not pandemic and there are "clean" ways to work around it (and I'm not talking about exploiting Flash Local Shared Objects to bypass cookie security!). I think cookie deletion is a much wider problem and it might have more impact on our analysis capabilities. Totally blocking a specific web analytics, yes, but would it be statistically significant? Surely not.