STR above certain thresholds is generally considered a services business more akin to a hotel, not passive rental income.Confirm with your CPA on the best approach to form and perform tax reporting for your short-term rental business.  

Is person performing test at vendor is qualified and competent?

While this may exempt it from being classified as a rental activity, active participation remains a requirement, necessitating compliance with three tests: spending 500 hours on the property, dedicating at least 100 hours (and more than any other participant), and performing all the necessary work needed.Additionally, long-term viability and consideration of depreciation recapture are important concerns.

In which markets have you noticed particularly strong performance recently in terms of rental demand and occupancy rates?

However, as the owner you still need to spend more than 50% of personal services and more than 750 hours on the real estate business on your own.Alternatively, short-term rentals are generally treated as active business income and therefore are eligible to offset w-2 income.Navigating the Real Estate Professional Rules"When measuring material participation, a married taxpayer is required to count any hours performed by his or her spouse, even if the spouse does not own an interest in the business or if no joint return is filed.32 While this rule is advantageous because it makes it more likely the taxpayer materially participates in the real property trade or business, it is a trap for the unwary in the real estate professional context, as discussed below in Step 3.""

Most architects (and Contractors) do not like to follow up on their colleagues work.My first thought though was that you should go after the Contractor (and possibly the Architect) for non-performance.

It will work for me not just for buy and rentals but for anything I decide to do such as building a ground-up spec home or buying a non-performing note or doing some lending.

It really performs a perfect job of improving the taste of the water significantly. 

Perform comprehensive due diligence on possible investment properties, which should include risk assessment, financial document review, and inspection.

HOA prices and restrictions is probably the next biggest thing to pay attention to as they will have a lot of influence on your profit margin and growth potential.