They don't owe you any money though. So what are you going to sue them for? You're not an employee, they don't have to pay you. If you actually care, I would inform them that you bought the site from someone else, and you did not know that it previously used adsense.
Just to backup my point: 8. No Guarantee. Google makes no guarantee regarding the level of impressions of Ads or clicks on any Ad or Referral Button, the timing of delivery of such impressions and/or clicks, the completion of Referral Events, or the amount of any payment to be made to You under this Agreement. From https://www.google.com/adsense/localized-terms (The terms of service you agreed to)
wait. so you had 1 account closed, and opened a new one and had it closed too? you violated their tos and you want to take them to court. Heh.
When you signed up for adsense, you agreed to certain terms and to give up certain rights. A few of the terms... "Any dispute or claim arising out of or in connection with this Agreement shall be adjudicated in Santa Clara County , California." "Google may at any time, in its sole discretion, terminate all or part of the Program, terminate this Agreement, or suspend or terminate the participation of any Site in all or part of the Program for any reason." When google doesn't pay a publisher, they refund the money to the advertiser and don't get to keep their portion. They have no financial incentive to terminate publishers. Unless you are talking about a lot of money (which wouldn't mean small claims court) I would just move on.
I think you should read up on the law before you go to court. There is no requirement, by law, or by their terms of service that they have to pay you anything ever. Adwords money IS credit back, you can ask almost any adwords advertiser, and they have had experience with this. As far as a 90% CTR on some site that you saw, 90% CTR is not against the terms of service, so they have no reason to follow up on that. It just means 9 people clicked on ads, that's not very many at all. That is probably why they haven't taken action. As far as warnings go, they have no reason to give everyone a warning. If they did, then fraudsters would know they could fraud all they want until they received their first warning, which isn't the impression Google wants to give to them. I do suggest you read the terms of service that you agreed to before making such outrageous claims against Google.
I used to attend some asset protection seminars and at one of them I bought a book called how to outfox the lawyers. It was published anonymously, shipped from a PO Box, and arrived in a plain brown wrapper One of the core bits of wisdom they offered was "Don't chase lost money." It takes your time, it takes your money, and worst of all it diverts your limited supply of positive creative energy into a negative direction.
I think the clams at Small Clams Court are highly overrated. I prefer the ones at East Side Marios... in the tomato sauce... they have great bread too.