@Lily Daudert the score is like a rule of thumb.

They aren't finding any of these leads for us and mostly doing errands but I just don't want to fall under the BRE thumb as paying commissions to an agent or some unlicensed activity (i don't know all the rules).

In the LOI or via email/phone call, give the seller an easy reason to respond: “This LOI was put together based on assumptions using our market experience and research data.

Make it easy for them to pay rent by using google wallet or square cash.

However, it is usually easy to rent individual rooms this late in the year - lots of {particularly foreign} students land at campus without a place to stay.  

Supposing the tenant has no lease it's easy to remove her with 60 days notice to vacate?

With a M2M lease, as soon as you realize that your tenant is dirty, you give them notice and find someone who won't live like a pig.In reading another post on a similar topic (you should search) someone posted that in TX, "lease rules" so apparently you can add things to your lease that supersede law and it's cool. 

It looked good on the BP flip calculator but didn't fit the 70% rule.  

Are there rules of thumbs governing this decision?

Though the reality is, the cause is an easy fix and the remediation can still be done without condemning the place for tear down.