Here are some other things to consider: 1) financing plays a big role in cash flow 2) maintenance/cap expense is much higher than many inexperienced investors believe 3) buy n hold is not a passive investment 4) forced appreciation can compensate for a lot less cash flow 5) especially for duplex to quad it is important to only use closed properties in comps; ignore listing prices.  6) with conventional financing you can have fine cash flow at below 1% rent to price ratio.  7) prop 13 is every Ca RE investors’ friend.  8) appreciation (rent and property) for financed buy n hold will produce better ROI than cash flow by itself.  

He ignored the advice and ended up in court when his ex girlfriend stripped the house and walked out leaving him with a 20k repair bill. 

Was this always prohibited, but the prohibition was ignored and has started being recently enforced? 

That's an instant-ignore offer, and both the person who made the offer and the agent who sent it get added to my list of morons who I advise clients that, "if they are presenting an offer, I am 99% sure we can hold out for a week more and get at least 20% more than that.

(ignoring shipping which I’m sure varies widely)• are there effective sources to seek units for sale (aside from Craigslist)?

Is it common for a seller to refuse to show at least a T12 before having a PSA or could they be hiding something that they hope I would chose to ignore during due diligence?

It's funny they completely ignore the option of professional property management ."

Ignore the property that helped you find them, as it may not fit your deal criteria.Excited to hear how you find an agent and your next deal!

All leases, past and current, it’s a nice side business most ignore. 

Sadly many tenants are ignorant and don't treat a rental like their own home.