Some of them list training as a service.  

Go talk to people that work with a lot of Section 8 Tenants.

After speaking to the listing agent I found that all but one buyer had the same experience.

I check Zillow for listed properties to see what they sell for.

Some of the more seasoned vets here know all about foundation repair, but for thought this could be helpful for anyone starting out.  60 seconds background:Houston is essentially built up on a swamp, couple that with back 2 back brutal summers with little rain, and nearly everyone I've talked with recently has some sort of foundation issues creeping up. 

These two are keeping me from listing the property and putting tenants in there.

I don't ever see anyone talking about this, is it cause no one owns their duplex for over 30 years, they don't do a 30 year mortgage, they rent a lot more then the mortgage payment???

We, as a Roofing Co, talk and deal with MANY clients that have aging roofs, and yes are fine, but the ins co is either wanting them to: replace the roof; pay a higher delectable; not have coverage for the roof; or drop them!

Are their listings detailed with good-quality photos?

My two property management companies provide me with monthly statements listing all the income and expenses.