There are several of those – but it indeed looks as if everyone stopped updating them. The one from Lookout had good details.
One of the few that still seems to be updated is Denper's Addons Detector:
Addons Detector (source: Google Play; click images for larger variants)
Not only does this app let you scan for ad libraries, but also for other development libraries, analytics and more. It's also a permission browser. This is currently the best rated app in this section, and was last updated less than a month ago – while being around for about 5 years.
My long-time favorite (next to yours) was Appbrain Ad Detector – which unfortunately wasn't updated for two years (I still hope they pick it up again):
Appbrain Ad Detector (source: Google Play; click images for larger variants)
Here I like the clean interface. This detector also lists plugins from social networks separately, shows which permission combinations raise concerns, and of course lists the ad modules, developer frameworks etc. If you use the Appbrain app to access playstore (it offers an alternative frontend), you are even informed of those before you install an app.
Both apps are available for free. I cannot tell how up-to-date their library knowledge is (especially concerning Appbrain's app, which was not updated for 2+ years), but would expect Denper's to be in front here.