Adsense has an accurate way to detect invalid activity. A site with more than 5,000 page views a day should not get over 3% CTR. Even above 2% is very suspicious. Google knows the average CTR of each market/niche. And if they detect something abnormally high CTR continuously, then they will disable your account for invalid activity. However, for a small site with less than 5,000 page views per day can have a high CTR above 5% once in a while (but not continuously) and that's ok.
I suspect your sites get very high CTR that's why they disabled your accounts. And rightly so. I have 6 high traffic sites and none of them averages more than 2%. The highest CTR I received by the end of the day was around 0.75%. The daily CTR average of all my sites is about 0.30% which is very normal.