The reason Facebook ads do not work is because they squander the money of advertisers, simple!
Last year, I sent a tweet showing his this screenshot of my Facebook page that had 3 Mafia Wars adverts in one go. That is Facebook wasting 2/3rds of advertising money in one go if doing a CPM.
Another example: In the past 2 months, I have been seeing an ad from GroupSpaces.The first time I saw the ad, I clicked on it to see what it was all about and saw they were recruiting. I saw the ad again and I ‘liked’ it. When Facebook kept showing me the ad, I disliked it and flagged it as repetitive, hoping it won’t be shown to me again so I could save the guys some money. 2 months and over a hundred impressions later the ad is still being shown to me. By repeatedly showing me an ad I have seen and clicked on, Facebook has wasted Groupspaces money more than a hundred times over with me. The advertising story of Groupspaces is the same with Startupers whose ads I have seen forever.
Ideally, Facebook advertising should be very efficient (unlike Google Adwords) since they know everybody who has seen and clicked an ad (you have to be logged in to see ads) but that is not the case because they deliberately squander the money of advertisers to increase their revenue. The faster you they spend your advertising credit, the better for them. This is plain wrong!
At least when next it seems your ad on Facebook does not seem to work, you know why.
Update: Co founder of GroupSpaces, David Langer, seems quite happy with their ad campaign on Facebook, he says they are fairly competitive with job boards. I still think FB ads can be more efficient if Facebook gives advertisers more options. e.g “Do not show an ad to someone that has clicked it previously”. “Do not show an as to a person more that 4 times”.