Ask HN: What is your biggest problem with in-app advertising

[snowbol]

Hi guys, I figured that many of you here build/have apps that are based on a freemium model, thus probably using some sort of in-app advertising.

I would love to hear your biggest frustrations with that as well what solution do you currently use. Feel free to be as detailed as you wish, I'm asking only for my own personal curiosity.

Thanks