I know there are numerous sites like Airdna - so you could use a multitude of them.   

@Peter Walther that may be true in some cases, but having bought and sold many CFDs across numerous states, I'd say that in practice it can be challenging to obtain title insurance with the messy chains of QCDs and AOLCs that we often see (and the fact that we, as the investor, have legal title but not equitable title).

There are numerous "illegal" apartments in NYC even though those laws have been on the books for years.

Some are but frankly, I believe most aren't.I've read numerous posts on Reddit where the Buyer or Seller is represented only by their Agent (and there is a Title Company involved) and when the other Party breaches, the victim of the breach realizes they will have to hire an attorney.Start out with an attorney in the most important investment you'll make. 

This house has been on the market for 3 years through numerous agents and price changes.

When he did his song and dance, then quoted that price,  I was blinded by all the money I was going to make on this deal :-)I learned how much things should cost on this reno vs. what he quoted.  

It seemed the most common reason for the numerous repair invoices was the managements lack of involvement with the property and tenants. 

Some of the most glaring problems are the fact that calls will routinely ring for 60 seconds or longer before being answered (they claimed several weeks ago to have solved this issue but I have told them numerous times since that I can clearly see through CallRail that they have not), there is a complete lack of consistency in the questions asked and information provided, there are errors scheduling appointments, their phone reps routinely lie directly to the callers claiming that they live in the local area but have only recently moved there so they don't know any landmarks (this is after I have made it explicitly clear to Call Porter that they are not to do this but rather be honest with the callers that they are not local but the owner of the business is), phone reps don't bother gauging the seller's motivation or equity prior to setting up appointments, and a multitude of other issues.

They pay rent on time but we've had numerous complaints from neighbors about them using bad language, being disruptive, and threatening.

Do some research on this site, and you will find some companies that are much more reputable, and don't have numerous outstanding lawsuits like the ones you mentioned.