You have to know your state landlord-tenant laws; they are on the internet:"In New Jersey, a landlord may need to give a 30-day notice to pay rent before eviction if the tenant has a history of late payments and the landlord accepts them.

For those that qualify for conventional financing its another negotiation tool, for those that do not its a way to get into real estate but many do not understand what it is they are signing up for.Regarding it being good for an owner, again it goes back to the borrower, if I have a borrower with 800 credit and I control cashflow its far different than someone with 540 credit.

What is the claim - that someone is going to sue them, or kidnap their child, or what? 

What I recall from Aaron's deals was it wasn't about finding ever larger seller financed deals, but keeping the old seller as essentially a PML....keeping you from constantly looking for new funding when you already have someone that agreed to fund you essentially. 

Any advice on educational courses or material that would help me learn multifamily as someone just getting started?

The plumber determined that the issue was caused by someone driving over the cleanout, breaking the pipe.

I'm mostly looking for easy disqualifiers like pets if they aren't allowed at a property, or someone looking to move in March when I'm vacant in January. 

I'd say Turbo Tenant, and this is from the perspective of a someone who commonly speaks with owners who've recently placed or have been placing their own tenants  - the general lean seems to be towards Turbo Tenant.

If you don’t want to spend money I’m pretty sure you could get someone to grade the surrounding dirt and add some gutters for your $5k discount and gain you will have added value and come out ahead.

If I don't do any of these courses, any other resources someone suggests for help in getting started on arbitrage?