I think the threat of lawsuits, and perhaps the realization that they're out of their league, is starting to hit home.

I'd also go through and look to see if there are major problems-eg is the water bill higher than expected because there is a leaky toilet or faucet, put some inexpensive low flow shower heads in. 

Any major mistakes to avoid? 

I currently manage a portfolio of 17 STRs, some are mine, but a majority for other owners.

I am a general business major and also currently working on obtaining my real estate license to become an agent.

These are almost always going to be balanced off by the majority that take longer and have lower returns.

Your a licensed R.E. agent, that is NOT a solo thing, it means your an extension of that broker, and anything you do in Real Estate has possible MAJOR implications from both the broker and or real estate regulatory boards. 

That tells me the majority is gonna struggle to pay rent.  

There are some concerns around taxes and insurance to be mindful of, but the job market in major Texas cities is unreal.

Personally I wouldn't feel comfortable trying to wholesale a relatives $1M home knowing that I am breaking the law if I cross over into doing anything that can be considered representing them in the transaction, and knowing it will only be marketed to people who buy properties wholesale (typically investors who don't want to pay retail prices), instead of the majority of retail buyers active in the market who are typcially willing to pay more.