Had Qihoo AV and Apus launcher on a low powered Moto E2 phone until a couple of weeks ago. Went back to the stock Google launcher and installed Sophus mobile security and phone has a lot more space.
Both Qihoo and Apus were pretty apps and Apus automatically grouped your apps into folders, something I've had to do manually since going back to the stock Google launcher.
I'm sure they were spying on me in the same way Google is spying on me, but they never turned me into the Manchurian candidate, stole my bank account, etc.
What they did was continually invite me to install still more apps, identify (but not remove) each others' apps as superfluous, and put more and more cr^p on my opening screen. When I uninstalled the Apus launcher, a couple of tools (memory boosters) stayed behind. Still run these occasionally, they tend to behave like any other memory booster-- they do flag Gmail and other Google apps as having privacy risk and invite me to put a separate Applock (a secondary code, I assume) on these apps. That seems like overkill to me.
I used the Lite version of Qihoo which had only the Qihoo antivirus engine, think the full version packed two others.
In all, it was pretty, packed lots of tools, took too much space and annoyed me with invites for other products. There are better products out there, but to call it spyware and not antivirus is a bit of a stretch unless everything is spyware. I expect that some pro-Qihoo editor will get into Wikipedia and clean that definition up.