"The first site on the vote list was tagged news/media."
What is the site? Without this information nobody can reproduce this.

"But there is no way to check this other than lifting my block on adware."
There probably is, if we knew an example.

"how about malware and phishing sites? I don't want to lift those blocks."
You don't need to.

"Wouldn't it be nicer if OPEN DNS would create a screenshot from proposed domain tagging sites"
I thought this is the case already. Not sure what you mean.
http://www.opendns.com/community/domaintagging/
From there you can get to the specific page with the details and screenshot by clicking the sheet link (e.g. http://domain.opendns.com/example.org), or to a frame view by clicking the domain name (e.g. http://www.opendns.com/community/domaintagging/domain_frame.php?domain_id=270477&category_id=21).

"...showing the next screenshot after each vote. It would allow us to give a lot more votes in less time"
Judging from a screenshot if a site is correctly tagged is more than dangerous and leads to lots of mistakes. We already have too much.

"What is the site? Without this information nobody can reproduce this."
My idea for improvement has little to do with that particular site. Whether or not you can reproduce it depends on if you have the exact same blocking settings (and possibly other settings, I'm not yet familiar with all OpenDNS settings yet).
But reproduction is not the problem. It is simple logic that a single site can have multiple tags or it can inherit tags from redirects and so on. That's not the problem either.
By the way I didn't bookmark the blocked page (why should I?) and my history is so full of opendns pages I visited today that it would cost me a lot of time to find that url again.
update, found the url
"Should slackersguild.com be tagged News/Media?"
http://www.opendns.com/community/domaintagging/domain_frame.php?domain_id=10044&category_id=33
That url gives me:
"Site blocked. searchportal.information.com is not allowed on this network."
"This site was categorized as:"
"Adware, Parked Domains"
and indeed adware is in my blocking list

"I thought this is the case already. Not sure what you mean."
When you click a sheet icon in the domain tagging list, you get a thumbnail, a very small representation of the actual site. A screenshot is IMHO full size and a slide show shows pictures one by one without the the need to go back to the domain tagging list. Judging from thumbnails is IMHO more dangerous than judging from screenshots. Anyone can see the difference between news/media and pornography on screenshots of such sites. Voting is IMHO not the best way to decide about phishing and other malicious sites. Perhaps the frame view can protect against spyware being installed to my system (is that the intention of the frame view?). But for example a screenshot from the real paypal site looks probably identical to a screenshot from a paypal phishing site, unless the phishers are really stupid. And the same is true for a frame view. Amateurs should not be asked to vote on such matters.

Phishing domains are provided by PhishTank. Others may have been submitted to domain tagging for phishing as well, however. Whereas the PhishTank community itself votes on domains, that is their gig, it is what they do, and I'm sure some are quite passionate about it. There is no way to automatically identify phishing, so some humans have to do it.