Now I have a good business that generates extra cash flow to buy homes again. 

Tenants are usually poorly trained.

@Matt Lefebvre How long does a contract usually last?

I currently live in Brick, new Jersey (Ocean county) and I've been house hacking for the last few years having had a roommate living with me in my extra bedroom paying me rent.

These people usually own very little real estate or have something to sell you (their advice, a turnkey in Kansas City, or a "free" seminar)I own 19 units in Oakland and have bought them all in the last 2 years.

That's because you usually have to go through so many deals before you get an idea what a good deal is suppose to look like.

@Chris Tracy @Joe Belman what expenses are usually too high?

I usually look at what other house in the area have and how much they are worth. 

We can usually financially break even if they leave it in good shape and we hustle to find a new tenant.

Though some are adding a rental registry with a fee, usually justified as an inspection cost.