My suggestion would be to select someone with the most forum posts or most reviews.

For the institutional we have a factright report they can review about us and for our retail investors we try and educate and be transparent.

Check out other online guides available here: https://www.biggerpockets.com/guides3.

Check the in person events and meetups in your local area, our online community is full of knowledge and folks willing to share and still nothing replaces the opportunity to interact IRL, you never know who you will meet and where that can take you on your REI journey. 

Connecting with local real estate investor groups, attending meetups and conferences, either in person or online, can give you advice + support as well!

For example, my client recently tried to do a deed transfer, and when I reviewed the deed history and names they were proposed on the transfer - there were discrepancies.

Review the days on market information. 

As mentioned no need to hire a private investigator just use an online service to do a background check.

Check out other online guides available here: https://www.biggerpockets.com/guides3.

By requiring licensing that you think is so onerous, which is usually quite easy to complete and reasonably priced  maybe $1,000 and somewhere between a day and 2 weeks of online classes, we can protect a segment of people that need protection.