The $20 you gave him went to his favorite habit - cigarettes, liquor, drugs, cat food.

Homeowner is unresponsive and unwilling to sell to anyone, likely due to some clouded judgement as a result of drug use (apparently, according to neighbor I spoke to yesterday).Is there ANYTHING I can do, speak to the bank/attorney/etc. to purchase the property ahead of auction/foreclosure?

Many people aren't right in the head without street drug!

. : )First step is make sure it is cigarette smoke and not some other kind of drug which is more expensive and much harder to remove from the property.If it's just cigarettes the extent of the cleanup will be relative to length of time smoking in the house and the frequency.It is labor intensive and does cost quite a bit of money so figure that into your offer price. 

Breaking laws which relate to drugs, housing, safety are grounds for eviction.

The short story is that we believe that the building is infested with drug dealers.

I was cleaning out closets to prep for paint and in the corner of the upper shelf found a baggy of what I assume were drugs of unidentifiable type ... and no I did not test them out to see what they were ...Another one that is more common but what I use as a "tell" that I'm likely to get a good deal is this ... for bank foreclosures, in my market they don't have to worry about freezing pipes so they normally turn the water service off ... well, for some reason some people still see fit to use the bathroom facilities even though the water is off.

It was two single guys, one of them a drug addict.

I remember seeing blatant drug dealing in a pretty central location four years ago along with lots of smells of 420.  

It has only happened once, and through amazing luck, they turned out to be the nicest drug dealers ever and helped pay to remediate the special venting they had constructed through my roof without permission.