Beware,

"A question that should be taken seriously"

It's difficult to say if this scenarion would effect the property value of homes in the neighborhood but it would most definitely be a serious consideration for those individuals that are looking to purchase property and checking for this information.

Sad but true, we find that most buyers don't consider this as a pre-purchase issue.

Of course it would bring the value down if the buyer or appraiser was aware of it. If they didn't know then it would be same market value as other homes...