It certainly does, but I'd say that it is the exception to have no influence from the agent in the evaluation. 

If reported early, the costs would have been substantially less and not the tenant's fault.  

Within my personal portfolio, I have raised rents on properties that had tenant turnover (pretty substantially actually, as the ones that turned have been in the properties for a few years and I've missed out on optimizing market rent during that time), but not on renewals. 

Both are solid options, having it paid off is great and keep in mind that will add substantial cashflow because you won't have a mortgage anymore.

And I've had them change substantially like this, both up or down.If a person is working more hours and getting overtime, getting more from government benefits, had a kid move out, etc., that can throw off the calculation.

However I have seen instances where a seller will definitely feel "cheated" if you make a substantial profit (usually $10k or more).  

Nothing that will substantially increase value though.

For building that skill set, I'd start by reading How to Win Friends and Influence People.For building actual relevant relationships, I'd find local REI groups / clubs and attend as many as often as you can. 

If the renovated units will get you substantially more in rent because the previous owner never raised rents you could even offer cash for keys.

Exploratory operations and development operations are the two types of investments that can create substantial tax benefits, if you simply invest in a stock of an oil and gas company, that won't help you.