Is Sidewiki evil? (Probably not, but it's annoying!)

Apparently the Google Toolbar has a new addition, Sidewiki. It's kind of passed me by, as I don't use the Google toolbar, but it's a bit misnamed.  It's not truly a wiki, but it does offer website visitors an opportunity to leave comments about a website or webpage. 

These comments are only visible to Sidewiki users (see picture). 

Unfortunately, the website owner may not only be unaware of comments attached to (and in many readers' minds therefore associated with) his/her website, but cannot control or moderate their content.

I've already added a Sidewiki blocker to Wonderful Life, and will shortly do the same to this website, and to the North Bucks Road Club, the Team Grumpy and the Northwood Wheelers websites. Of these sites, Flies&Bikes has never attracted many comments (so I presume not many Sidewiki comments), though Wonderful Life has been more active in that regard.