Their big claim to fame is anonymity, and better BK treatment for debtors.

I'm only transitioning into trusts for anonymity so if you search my name on title nothing shows up. 

The point of using a land trust in real estate is for the beneficiary to remain unknown/anonymous for as long as possible.You can ask the trustee for verification that they are in fact authorized to sell the property held in trust (it's not always the case that they are, you should check).  

Yes I would approach them with a wad of cash and simultaneously place an anonymous call to the Codes department because of the condition of the house.

For the purpose of maintaining  anonymity and gaining some liability protection and estate planning advantages, I own my multi's in an LLC and manage them with the S-corp.  

He said the investors he worked w/ like to remain anonymous and don't want there information shared.

You should be very aware that if you transfer property into an LLC that you could trigger the "due on sale " clause and have lender accelerate the loan...another issue to be concerned with is the potential transfer fees possibly levied on mortgage balance depending on your location.I think you should look into purchasing the investment property in a land trust which not only provides anonymity, but also gets around the two issues I mentioned above.

I working for 20 units within 2 years (duplexes, tris/quads) here in DFW and would like total privacy/anonymity. 

It really hurts when you are spending money to maintain your property and your neighbor looks like they are shooting for growing a jungle.You could always make an anonymous phone call to the HOA, city or township (who ever oversees your neighborhood) and check about the regulations governing property maintenance and then discreetly turn them in.

Do not name the contractor who questioned it, but word it as anonymous as you can.