A LOT of nepotism
Pretends to trust its employees but high micro managing at the end.
Pretends numbers are not important (high hypocrisy)
Blackbox even with its employees.
The market itself is fishy (online ads in mass). When you think about it, Criteo is this annoying entity pushing you thousands of ads per day and enabling for mass consumption. Although it's all legal (completely), the methods are not great. In depth, Criteo's services just don't serve anyone any good. But, it does work. They make money and you will earn money working there. Just know you will contribute to one of the most indecent internet practice of nowadays.
They hire new employees with a higher salary than for the existing ones and they ask those new employees not to divulgate, even lying to them saying it's forbidden to talk about salaries.