I tried to advertise a PTC but my ad has been refused and it has never been shown to anyone. Now I found my account suspended and I don't know why. I also don't understand why are they so strict - I submitted that ad without writing it was a PTC or Paid to Click service meaning that I didn't even encourage users to click on the advert. I don't want to advertise further in the adwords network so I wont send letters to the customer service, but I basically don't see the way they think. Obviously it isn't Google's business what's on the webpage after someone clicked the ad 100% relevant to a website.
I encountered the same thing myself. Since I decided against using Adwords afterwards, I never really tried to discover the reason(s) why they suspended my account. However, I did try to contact Google about it -- received an extremely vague and general reply that didn't answer my inquiry at all.
Sometimes google give you a reason, sometime they don't, you have to scrach your head and find out yourself. try to improve user experience? to some adwords user, this is a very bad experience. I have such experience a few years ago... it's like talk to any auto-responder...
1. Google Policy 2. There robots may ave made a mistake 3. You should e-mail them and ask them about it.