I've never heard of demolition as a solution for the problem, but it certainly seems like as much as you can do to a structure.I would find out what it costs for an environmental survey that includes soil testing.

@Haider ZamanProperty Manager Job Purpose: Maintains property rentals by advertising and filling vacancies; negotiating and enforcing leases; maintaining and securing premises.Property Manager Job Duties:Establishes rental rate by surveying local rental rates; calculating overhead costs, depreciation, taxes, and profit goals.Attracts tenants by advertising vacancies; obtaining referrals from current tenants; explaining advantages of location and services; showing units.Contracts with tenants by negotiating leases; collecting security deposit.Accomplishes financial objectives by collecting rents; paying bills; forecasting requirements; preparing an annual budget; scheduling expenditures; analyzing variances; initiating corrective action.Maintains property by investigating and resolving tenant complaints; enforcing rules of occupancy; inspecting vacant units and completing repairs; planning renovations; contracting with landscaping and snow removal servicesMaintains building systems by contracting for maintenance services; supervising repairs.Secures property by contracting with security patrol service; installing and maintaining security devices; establishing and enforcing precautionary policies and procedures; responding to emergencies.Enforces occupancy policies and procedures by confronting violators.Prepares reports by collecting, analyzing, and summarizing data and trends.Updates job knowledge by participating in educational opportunities; reading professional publications; maintaining personal networks; participating in professional organizations.Accomplishes organization goals by accepting ownership for accomplishing new and different requests; exploring opportunities to add value to job accomplishments.

One example was the "rent survey" from the appraiser was like $1400/mo rent and I already had it rented for $1800/mo. 

So after a couple years of his crazy bull I ordered a survey.  

@Sean Wilt I saw a friend filling out a survey and although he loved his job he filled out everything in the middle.

His response seemed weak to me, said he can't offer advice as far as the law is concerned, because its an "as is" property, attorney will order survey, title reports, etc.  

I'm not sure if FL uses metes & bounds or rectangular survey.

A rate survey for upstate New York commercial properties by Rynne, Murphy and Associates for the First Quarter of 2010 indicates equity yield rates for small multi-family suburban properties in the range of 11.00% to 16.00% with an average of 13.25%.

The county appraiser says there is 2363sqft, however I don't think it has had another survey done in, lets say, 57 years.

In an ideal works one should take tenant surveys and see if your tenants are relatively happier than other tenants in the area.