From what iv noticed, the big time players who own hundreds of doors typically own their own PM company.

Sellers did not allow us to get professionals in to give estimates for a french drain before closing (yes, our red flag we should have walked away with), but agreed to lower closing price. 

A few of my red flags: He didn't call me, she did. 

After attending an awesome BP meetup in Philadelphia (hosted by @Troy S.) some red flags have come up regarding the structure we're looking to use to fund our first flip.My partner, @Phil Sabella, and I have connected with a financier/partner who does JV's.  

I agree with the answers above and that condos have a lot of red flags for STR investments.

Less governmental involvement, restrictions, fees, red tape, etc. here in SW Florida. 

Step by step you are working your way to being an independent player where you can do the deal on your own eventually.  

The company red tagged it.

The devious and unethical players can rip you to shreds in the commercial space if you do not know what you are doing or do not have good representation. 

That right there is enough of a red flag for me.