I tried adbrite as an advertiser a couple of times and was disappointed. Lots of foreign traffic who didn't stick around on my sites or click many ads; in contrast to my usual ppc traffic from the search engines. It would be intersting to hear from anyone who's had success with them as an advertiser...
I am noticing the same as you. Most of my traffic is foreign where they are not sticking around for long even though I am advertising my site on sites that are on the same topic as mine. I have a arcade type site aswell, which is getting more and a little better traffic from Adbrite, but even though it is getting this, I am still making a loss as the cost for the advertising is alot more than what the traffic is making me in money.