In addition to the tools listed, I use Google maps to also learn an area. 

Create additional columns to the right of your leads with your mailing dates as the headings.  

Have any of you experienced this and know of an effective way to prevent the additional waste?

Be sure to understand the product warrantee (ie expected lifetime).

Figure out what you have into the property for total cost and than run a highest and best use analysis.This should tell you whether to rehab what is there or tear it down and build something new with the same asset class or a totally different asset class ( commercial, etc.).Additionally once you find out the highest and best use then look at the TIME required to develop that use and receive income from it or sell off.Some people will get the fire department to do a "controlled burn" on the property and use it as a fire exercise.

Although to be fair its not like podcasts, products, books, gurus, etc out there paint a clear illustration of what REI failure looks like. 

Check with an attorney or the state MHA for additional guidance on that.

@John ArendsenIn addition his debt to income ratio is not very good but there is plenty of equity.

Let me know if you need anything or have any additional questions.

Also, you can make a stronger offer if you are using cash.In my area, and given the units that I have been considering, this would result in about $100/m additional cash flow after debt service, and assuming 8% vacancy, conservative estimates for taxes and maintenance.