I bought pixel ads for a year on one of my sites (about to expire). When I do a link:www.mysite.com in Google it shows no backlinks. However when I do a backlink check in Yahoo or other engines, it shows on average around 4,000 backlinks and all from the pixel ads. The reason is the pixel ads were displayed on a forum as well, so every new topic created a backlink. So I guess it depends where you buy it from, but I definitely think they work. I have a PR5 in Google for that site, not bad I guess.
For SEO it's not worth buying. Unless you buy loads or with a whacky shape so people start blogging about it and linking secondarily.
Pixel ads are only really worth it for traffic, not SEO. Google is already notorious for not always following image ads--and they figured out the whole pixel things a year ago. Their policy is to ignore what they consider unnatural links, and pixel ads certainly fall into that category. And the pixel thing is dead anyway. Save your money
My guess is yes, purely based on the fact their would most likely be more than 100 links on the page. I could be wrong though, but going by Google's rules, I think it would be classified as a link farm.
I check AdsExperiment and it seems that no ads has been sell? How popular? I wouldn't personally visit a page full of ads... You don't even need a quality website to get include in these pixel sites, just money
yes google follows the pixel ads , but i think pixel ads look like link farm . there are too many outgoing link on pixel ads page because of this it will not help your your site about serp and page rank