We agreed to partner where I would remediate the septic and code violations at my expense.

Your future tenants will notice it, so it effects your value.I would also try and remedy the reason for the dents, i.e. door stoppers.

A 4 hour drive plus time to remedy a situation is a major undertaking with a full time job.

You did not remedy a cloud on title / fulfil your agreement to sell. 

And landlords must learn the art of the negotiation, how to remedy without eviction, how to flex there other legal remedies at hand, learn the financial side of contracts and how to leverage and utilize in conjunction with negotiations. 

If they have violated the lease, you can follow the remedies in their lease.2) Depending on your sub-market, the prospective tenants may also be pot-smokers so not care about the smell.3) Find ways to mitigate the smell to the other unit. 

I sent a picture to a friend who used to work with mold remediation and he said it was consistent with mold.

Now, I’m paying thousands of dollars out of pocket to remedy these issues. 

If the company finds evidence of mold, offer to pay for the test and the remediation.

Charles,I attended a mold remediation seminar last year.