Most agencies charge you a management fee by the percentage of the adspend you spend with them. So if you are spending $10,000/month with them, they get $2,500/month. There’s nothing wrong with that, but here’s one “small little conflict of interest” – they want you to spend MORE, and MORE, and MORE! And that’s regardless if they are doing a good job optimising your ad dollars. They could be spending more of your hard-earned ad dollars just so they can get more fees out of you.