At adbuff we maintain a high quality environment for our advertisers by ensuring their ads will be effective on your website. That means their ads are not buried behind dozens of other ads.
While there is no hard and fast rule about how many ads is or is not acceptable, the main focus of the site should be on the content and not the ads. If most of the blank space on your site is occupied by ads then it's unlikely we will accept you into the network.
In addition, if you choose to run pop-up ads, they need to be subtle, be easy to close for the user without any prompts, and not play any sounds. It's a much safer bet to disable any pop-ups on your site.
A guaranteed way to pass the excessive advertising threshold is to limit the amount of ads to 3 and have zero pop-ups.