I was definitely a very good tenant who put up with a lot of nonsense (windows that dont lock, chipping paint, mold, ancient plumbing, rude property manager, etc.).

I am sure it is way more complex than that but I am sure someone on here has more experience with this issue that is far less ancient than my own knowledge.

I'll paraphrase an ancient saying, "he who holds the gold, makes the rules."

DE is basically ancient microorganisms that died and left their sicila (glass) skeletons/shells behind as microscopic shards of glass. 

I had a unit where I had laid laminate in the kitchen around a cement pad for the ancient stove.

The mobiles are ancient (pre-70's I believe, but the owner installed 1/2 drywall and regular 1" thick subfloor inside.  

The appliances are ancient and I'll replace those.

We have a duplex with an ancient AC system.

that is never true with any seller - it doesnt mean they will defraud you but that simply is not true ans should not be true.even if there is legal redress - that is expensive to prohibitavely expensive and it usually cannot be put into the numbers ahead of time.... as others have said - it is a terrible thing that happened and there are plenty of other places that have unscrupulous people but that is just part of today's landscape - and why an ancient phrase - caveat emptor - was coined.

It may not have been a recent murder, it could be an ancient Indian burial ground or the portal to hell like in the Amityville Horror.