Its known that my places are nice and clean and safe, that I will respond promptly if there is a maintenance need, and that I will enforce my lease.It wasnt always this way.

As soon as they found out they went over and asked the tenants to remove the dog from the property, which they promptly did.  

Twenty-four hours is presumed to be a reasonable notice in the absence of evidence to the contrary.(9) Promptly commence an action under Chapter 1923. of the Revised Code, after complying with division (C) of section 5321.17 of the Revised Code, to remove a tenant from particular residential premises, if the tenant fails to vacate the premises within three days after the giving of the notice required by that division and if the landlord has actual knowledge of or has reasonable cause to believe that the tenant, any person in the tenant's household, or any person on the premises with the consent of the tenant previously has or presently is engaged in a violation as described in division (A)(6)(a)(i) of section 1923.02 of the Revised Code, whether or not the tenant or other person has been charged with, has pleaded guilty to or been convicted of, or has been determined to be a delinquent child for an act that, if committed by an adult, would be a violation as described in that division.

Be prompt with your responses, fair with maintenance, and firm with the rules established in the lease.

Not everyone responds to texts promptly, or at all.

Prompt response to maintenance requests.

Thanks for your prompt responses!

The Federal withholding requirements can complicate a 1031 Exchange transaction, but they are manageable if addressed promptly and proactively. 

Might be a few small parts and shows the tenant you're responding promptly.

The common advice seems to be, work at a fix before buying.Bring it to the seller in a tactful/reasonable way and just let them know that it’s a concern and I want to have it further evaluated prior to closing.I am hoping that they do not have a problem with it.Someone suggested threatening to walk and/or notifying bank of our suspicion and the fact that they will not let us inspect.I am trying to avoid any kind of antagonizing approach in the hopes that this can be resolved/mitigated without too much issue.I do like the property and not wanting to walk away, just want to figure out a way to resolve before I take ownership.For now, my summary action plan is to move forward with tactfully notifying the seller of my concern and desire to inspect, complete an inspection, mitigate or come up with a plan to mitigate and then also empower tenants to work with management at addressing mold by reporting any leaks in a timely manner to allow for prompt fix, as well as possibly suggesting they purchase damprid which I hear helps with moisture and making sure to pass on educational/informational material on indoor air quality.There is an indoor air quality guide that someone in a facebook group that I am part of suggested, which I intend to make as part of my lease addendums/guides for tenants.https://www.epa.gov/indoor-air-quality-iaqI do have a contractor lined up to address some regrading issues and also visible cracks which could be where the moisture is coming in through.The challenge is that mold is everywhere and I do not doubt, that we will find something, the key is to work together to “address/mitigate” vs. turning a blind eye which I suspect may have happened here.In the end, I like and appreciate all the comments.I think the comment that sums it up well is @ Clay Hartwig’s comment that the problem is not limited to just the tenants getting sick, the problem is also in working to mitigate moisture which could essentially kill the house.Thanks again to everyone that offered suggestions on what to do here.