Cody,, no two are the same that's why there are no rules... you have to look at each one and do the simple math.. you can napkin math it using the 70% ARV minus rehab that usually works OK.but what I laid out took me 3 minutes.. just put your formula together and use it each time.So ARV  =10% sales costs =  (  )SOW  =  (   )Carry costs = (   )your fee  =    (  )15% profit on gross sale for end user  = (   )   now this is a rule of thumb others could do it for less others could come on BP and say they won't do it for less than 20% but I know west coast is very competitive and 15% on gross is what we try to make on new construction.. and we usually hit it OK.. but sometimes its 10 to 12%  but then we might be selling 20 plus homes in 10 months so its still a big number in total.But run it by your buyers and see what their profit margins need to be..

In my opinion, there's no excuse for staying in his property and not paying the rent other than being denied safe/peacable and or healthy/sanitary habitation.

See my non-professional numbers below:I was doing a quick on-the-napkin calculation of buying 15 of $100K homes, which would allow for ~$3636 in depreciation on each property per year, ~54K in total tax write-off/income reduction per year. 

When the water closet backs up at the 4" sanitary T, waste goes upstream to your tub.

Like down to napkins or sunscreen.

A good strategy that worked for me flipping remotely was to filter my potential properties through my napkin heuristics based on pictures and advertised info, then if it passed that test, then have my trusted agent do a walkthrough with me on facetime while we go down the checklist of items and estimate them, and if it still worked as a deal, then we would offer, and after acceptance the crews go out and bid on it. 

Some folks here buy houses making their numbers on napkins (not me thought).  

Get them drunk and make them sign purchase agreements for their properties on a bar napkin.

I have language in my lease about keeping the property in sanitary condition and not storing hazardous materials.

From the inside, this usually means something like a perimeter drain, piped to a sump pit and pumped into a sanitary sewer (if allowed) or far away from the house to a daylight drain.