Thanks, I hadn't heard about this. Per https://bugzilla.mozilla.org/show_bug.cgi?id=1406647 where Firefox is tying in with Cliqz:

> Cliqz is a well-known Adware from Germany[1] and it was a plague

Not sure what data Ghostery is collecting now, or how opt-in vs. opt-out has changed (if at all), but it looks like based on the reputation of the new owners I will no longer be using it.

Edit: the small HN discussion seems to cover this a bit more evenhandedly: https://news.ycombinator.com/item?id=13652126