99.9% of "black mold" is common mildew. So before you freak yourself out and before you go looking for legal remedies, have a professional evaluate the problem and come up with a recommended solution. And don't go with one of the companies that advertises that they deal with "black mold" or "toxic mold," because those guys will find it whether it's there or not. Go with a reputable water damage company. Mold and mildew is, at its source, a water issue. It will never go away for good until the source of the water is located and resolved. Once you have a good professional idea of what you are facing, then you will know whether or not you want to take on a lawsuit to deal with it. If the expense warrants taking on a fight, then you will have to decide if you can prove that the sellers knew or should have known that it was not properly dealt with and failed to disclose it. If you have that proof, then you will have a case.

I agree with Mr. McCormick. You need to find the source of the moisture/ water leak in your home. When I worked in personal injury law, the only mold anyone was interested in was Stachybotris mold.

Specifically, Stachybotris Chartarum is the one that is a problem. It produces mycotoxins that adversely affect human health.

I would focus on the water problem, and remediation, to determine how big of a problem you have, before running off to the courthouse to sue someone.

You have legal recourse. You may present a demand to the selelrs and their broker to fix the problem, If you can't resolve it to your satisfaction, you can file suit for fraud and breach of contract. You'll have to hire qualified inspection done and present the estimate for repairs, or do the work and present the actual bill.

You may have "legal recourse" as Mr. Nelson says, but in order for your recourse (suit for fraud and breach of contract) to result in your winning enough money to pay even part of your legal bill, you'll have to prove significant harm to your health, property, or other damages. If the mold is the usual kind, the judge or jury might give a verdict for the defense, or award you $1. Having a right to sue and having a good case are different stories.