Did the Last Occupant Die Here?
Copyright (c) 2012, Deanna and Jim's GOLD Team
If the last occupant of a house had AIDS or HIV there is federal Fair Housing Law that governs.
Otherwise, what the listing agent can and cannot disclose when asked this question varies greatly by jurisdiction.
In Northen Virginia...
Answering this question constitutes disclosing something which is not a material defect. Many listing agreements pledge the lister not to disclose seller information other than material defects.
Of course, if the owner of record is "Estate of John Smith" certain speculation may arise.