While doing research for answering this question I found out that Stack Exchange logo displayed under the 'We the undersigned…' section of Acceptable Ads main page. Click on the 'Additional organizations' link to expand the list of organizations. Here is the screenshot:
Acceptable Ads manifesto says:
We, the undersigned, want to make the Internet a better place for
everyone. We'll start by getting rid of obnoxious ads... read full
details
Also, as per Dean Murphy 'Crystal iOS app' developer:
Acceptable Ads is an initiative, supported by 3 of my favourite
websites (Reddit, DuckDuckGo, Stack Exchange), that encourages and
promotes the use of better advertising on the web
Also found ticket #1905 that was opened on 01/29/2015 (which was closed on 02/09/2015) for Adding Stack Exchange to acceptableads.org which states:
Stack Exchange would like to join the Acceptable Ads Manifesto on
acceptableads.org.