My wife and I recently fixed up a house to rent that was previously
owned by a heavy smoker. The entire house _reeked_ of old tobacco when
we bought it. We removed all the wall-to-wall carpet, we screbbed all
walls and ceilings with bio-degradable TSP substitute, primed (with
Kilz) and painted (two coats) all walls, ceiling and trim. The oak
hardwood floors were thoroughly scrubbed. We also had professionals
come in a clean the HVAC ducts, replaced the standard air filter and
are now cleaning the broken electrostatic air cleaner in the HVAC.

However, our new tenants say there's still a stink of tobacco smoke,
and they're concerned enough for their 1-1/2 year old son's asthma that
they're saying they'll have to move out if we can't get rid of the
smell.

We can't go back and re-prime the walls and repaint with something like
B-I-N (which I discovered doing some research in the newsgroup). What
other _reliable_ options do I have for abating the old smokey stench
the tenants say is in the house?