Talk used to say that anything above 10% would make your site flag up at adsense.. however, I've had a steady 10 - 20% ctr on a site and never had any issues but I do nothing dodgy. The site is good, plenty of content, unique, no dodgy backlinks etc etc etc just people visiting the site click on the ads ... a lot.
There is no "safe" CTR rate, some sites have higher CTR, some have lower. I had high CTR on some websites and nothing happened. Of course it is hard to expect that a website can have 90% ad CTR and to be legit, but nothing's wrong with 20% CTR.
get good CTR by (Good traffic and Good amount of valid Clicks), it is called (Clicks Through Rate), I.e : 1000 visitor a day + 100 clicks a day = 10% CTR "This could generate 10$ based on your CPC) 1000 visitor a day + 10 clicks a day = 1% CTR "This could generate 100$ based on your CPC)
I totally agree with J.P and pozer. Don't worry about CTR, but your site's quality and your own activities when promoting it. I have one site where I almost always get 15% CTR. No problems ever. Forget about the myths and focus on your audience, deliver a site they want.
Your CTR will really depend on the your traffic and your audience. I have two websites one gets CTR 10-20% the other one gets low single digits, same ad type, unique quality content on both just different audiences, so I wouldn't worry about the CTR as long as your not doing anything shady, you'll be fine. However I would be on the lookout for sudden spikes in hits, for example if your CTR is 10-20% but jumps to 25% that's something you want to explore.
Exactly. If you have quality content, you're a great money maker for any ad network. They will praise you, not punish you.