There are many new ad networks nowadays, many will cheat you, some will be honest networks. I will not judge any network but before you try new one, just check:
-company adress and data, if it’s exist and where, honest networks are in USA, EU and in Israel (except Mobario^^), it’s sad but rest of world should turn on yellow light for you, because there isn’t any law protection if something wrong. Sorry Chinese, Russian or African networks, it’s sadly true, it’s your country law. Many ad networks from China like Mobvista, are honest but if somebody want to cheat you from China, you can’t deal with them. The best method is using Google Street Map to check if adress exist.
-check workers on linkedin or something like that, if they real person, ok
-don’t listen representatives that new network is compliant with Google policy, check it yourself, use:
*dex to jar tool
*jdgui
and check the code, if something wrong, avoid it to not get ban.
-if your ad network is displaying porn ads or virus alert(allowed but imagine what users will think after see ad like “you have virus”), disable or delete it same day