Killer price.    

Hilltop is a killer location and as well what has already started to "arrive".

The bigger investors have enough volume to overcome crap like this but for us smaller guys it can be an absolute killer.

Really it all comes down to the roof, South facing is fantastic, East-West is workable but less efficient because you must cover both side, North is useless, Shade is also a deal killer.  

This implies either killer off market deal (hard to find, typically needs work and/or has risk) or great value add (typically require work and have some risks). 

Not providing info is a killer no matter how much money they make so #3 would be out and 1&5 don't have any money. 

So, I think the hardest part of wholesaling, with a full-time wholesaling business, is keeping a good team in place as well as having a killer automated and well oiled system in place to handle the volume that is required to scale = make a living (we use Podio and it is AWESOME).  

HOA's are probably a killer, not to mention the cook county tax hike, but you could seller finance the unit if they would be willing to do that.

Taxes can certainly be a killer though.

I typically stay away from condos and townhouses due the HOA being a deal killer.