I just tried out loading blocked content, and, well, it doesn't load. :-) Not with the first click, at least.
To be precise: I tried some blocked ads. None of them displayed anything when I clicked for the first time. OW shows that it's loading stuff, but then:
Some became simply blank (white; or maybe page background, I don't know) and were not clickable afterwards.
Some stayed the way the were, and after the second or third click showed the blocked ads.
I just tried loading the site without blocked URLs—and the ads were still not loaded. That was because they were all known ad sizes.
So my guess is: If the same ad triggers several blocking rules—known size blocking and/or more than one rule in the URL blocking list—only one blocking rule per click is taken away. Please fix this so that all rules are abandoned at once.
This guess doesn't explain the blank behavior, though. What could that be?
My test sites were
www.macosxhints.com and
http://www.storagereview.com/guide20...Objective.html. The latter one shows the "blank" behavior with the ad image just to the right of the Storage Review logo ontop of the page.
My URL blocking list:
/ad[^dm]
\.swf$
\.falkag\.
some\.ad\.com