How various times have you been to a website and could not know where the ads stop and the content begins? You spend a few minutes trying to figure out what the site does? And then you leave.
Knowing when is enough can be a tricky thing. It also depends on what you’re trying to do with your website. If your goal is only to sell stuff, then having ads on a 95% of your website is a good thing. But if pushing content on site is your thing, then 30% is better. Need fine ratio between content and ads on the website. This ratio can even be seen in the keyword/content relationship also. Search engines start to deny websites that have over a 20% relationship. Also, people reject websites that have too many ads. Although no one has come up with a survey or poll to figure that out yet, it doesn’t taker a rocket scientist to know your website is not working. Maybe they have a survey page, but it had too many ads. I would have to say that the ratio should be between 20% and 30% depending on your page. ( Conversion Rate Optimization Tips for e-Commerce Sales )
Your page should be easy to navigate through. Your content should be easy to find. Yes, there are many tricks to make the ads look like your material to trick people into clicking on them. But remember that if people can’t find what they need, they might not come back. Would you use trick someone one time for a click or have them return for many more clicks.
You can experiment with your ads. Try some pages with a 45% ad ratio and some with 30%. See how each of these pages work. You can even try different placements. Some people believe that ads content should be aligned Top: Left. Others Center Frame: Left Heavy. The bottom line is the ad content must be in plain sight.
We live in a quick world, multi-facet, and multi-tasking. People would click rather than scroll. So anything that belongs to the fold (the term applied for anything under the page you see in your web browser) is not necessary to be very important for you. Hence create smaller pages.
Now with smaller pages, the ad content proportion can go out of hand. So you necessitate knowing when is enough.