That being said, just because you saw black spots on the door or in the basement, does not mean there was necessarily a safety issue just by being in the home. Not all mold is dangerous - it would have to be tested to determine that.
And.......anything that obvious is......well, obvious. They certainly didn't do anything to try and hide it, like wiping it down with a mixture of beach and water.......... it was out in the open......the nature of it is yet to be determined. Only an expert in mold testing and remediation can give the answer to that question.
In OH, owners are required to fill out & sign a thorough, 4 page property disclosure.
However, in the area where you & I live, we have foreclosed homes owned by banks. The banks sell their homes "as is, where is." My guess is that you were looking at a bank owned home.
I suggest that you use the services of a Buyer's Agent. A Buyer's Agent will represent your interests, but his/her commission is paid by the Seller.
When you find a home you want to buy, make sure your Buyer's Agent includes an inspection contingency. You'll be able to hire an inspector for the home (including the lot); radon & pests. I have an inspector located in the area you & I live in who, does mold remediation, if mold is found by him. When I am acting as a Buyer's Agent, I always recommend his company. If you would like his contact info please call me.
Don't be discouraged by the one house you saw. There are good homes in North Ridgeville with some great prices.