Thats a tough one...one thing to consider if You bought the Land then had someone come in and make You clean it up any ways that could very well happen?I'd talk with someone in the Area/County that could answer Your questions...like the local ASC Office,County Commisioner,a local Conservation Agent any type of Land Commision You have may help?
You need answers to see if You can rent a Catapilar or Backhoe and cover up the trash pile or if it has to be removed and put in a local Land Fill or would You have to pay someone to remove it properly,Yeah it would definetly be a deal breaker for me!If the previous Land Owner would work with You and drop his price it may help in the process/cost of You cleaning it up?Find out first what is needed to make things right before You sign anything or hand over any amount of money!