I assume this would create a big difference on my tax liability since it would be cap gain vs ordinary income.

The value of the property would be considered taxable income and you must pay ordinary income tax on it.

Of course, since the payback is variable, perhaps the investor holds a tax consequence, even if I pay the capital gain / ordinary income tax.Has anyone experienced that?

As Brian said, STR properties are taxed no different than ordinary rental properties.

Expenses must be ordinary and necessary.

This is the tax IRA must pay, then when you take distributions at retirement you would have to pay ordinary income tax. 

Flips are ordinary income and Rentals are passive income.

You’ll pay recapture tax on the depreciation while it was a rental at ordinary rates, 25% max.

However, I've found that by regularly checking Zillow, I can find relevant listings about as well as those automated searches.I've heard that agents can see information in MLS that ordinary mortals can't, and that this information can be valuable.

Some minor monthly expenses but nothing high or out of the ordinary.