They algorithm somehow ban you. My last account - new company, address, pure new pc, new internet, new gmail, new phone number, new bank account and new cc ( all real buyed stuff ). I run for 7 days, and then got banned for suspicious payment ( what give no sense because the cc, bank account and everything was real, and first time used ). I also used new domain, hosting and content.
So in the time I got banned for suspicious activity I send them appeal trought theyr form ( yesterday ). This morning I got second ban ( circumventing system ) - I use Hotjar, and I see USA visitor ( my landings are for europe ) come to my landing page, and see there is affiliate links. Got email where is "this decision is final, the account will not be reinstated. Please avoid creating additional accounts, they got same suspensions. Our team will not be able to give you any more specifics on the suspensions"
There should be some things that connect your account to previous one that was banned before, but I think mostly they work like - you setup campaign and run on keywords that may be risky for them, they just ban you ( weightloss, hack, gambling etc ).
I still see a lot of people promote blackhat cpa offers for long time. The key is stay under radar - don't rise budget too high and too fast, keep it low and slow, but for me its now counterproductive. Without proper scaling isn't worth logistic for new accounts, and feel when you see your account is banned again.
Congratulations to all that is still doing that, and I know there's a lot of them, but I give up on fucking Adwords