They don't necessarily care about any changes. 

The best thing to do would be hire a professional exterminator.

What professionals do I contact?

That means that the prior leaks and soil/groundwater contamination have already been taken care of. 

Ask a professional like @Michael Plaks. 

I would like to share a success story that outlines the importance of networking and the careful selection of location for real estate investing.

To successfully invest in a property for steady income, establish your investment standards, research the market thoroughly, assess your financial preparedness, connect with local agents, property managers, lenders, and other investors, analyze properties carefully, consider various financing choices, do your homework before making an offer, and negotiate and finalize the deal.

Be careful the property isn't full or problem tenants, code violations etc. 

Taking the details from the legal description and plat map, a surveyor carefully measures the legal boundaries of your property.

Some simply care about the value, condition, and DSCR others will look at DSCR + Personal and Business Income and will use a global cashflow ratio.