what is BoomUserList in the keyword performance report?

[bgraves]

I've noticed that when my campaign doesn't have any keywords (ads
only) but there is still traffic being reported on kwSite called
"boomuserlist::23287" with a kwSiteType of "BoomUserList". Also, even
though there aren't any keywords, it still gives me a keywordid. Is
this "fake" keyword or something? I can't find it in the account or
when I get the keywords using the API (probably since there aren't any
keywords in this particular campaign).

[AdWords API Advisor]

Hi,

A boomuserlist in this report corresponds to a CriterionUserList in
the API:

http://code.google.com/apis/adwords/docs/reference/latest/AdGroupCriterionService.CriterionUserInterest.html

This is the criterion type used to associate UserLists (Audiences)
with an ad group.

Best,
- Eric Koleda, AdWords API Team