We suspect this for a long time.
Since we got this information over and over again from visitors but we never caught them.
There are huge traffic leaks if you compare server, cloudflare and webstats
with the exoclick publisher results.
Especially since they are back on xhamster.
Exoclick Support declines that.
Alone the fact that exoclick runs a second network
https://main.exosrv.com to serve tna and xhamster
and that they still run the popup campaigns of the Ramnit spreader tuberl.com
Take this company far from it what they indicate and explain on their homepage:
TRANSPARENT SELFSERVING INDEPENDENT
There are some newer reports out here that Juicy Ads did the same.
Best Regards