I have 3 rental houses and couldn't be happier, I had one problem tenant who left place damaged and had to take to court but I got a decent amount. It is a bit of luck on finding good tenants, but I find just meeting them in a short time you can learn a lot about if they will be good tenants, there is so many little things you pick up on when you've done it enough times. For the example above, things like clogged toilets are tenants responsibility. The only time i've had to go in and fix something one caused was a piece of glass in dishwasher drain causing it not to drain, but not really a big deal. Most of my tenants have stayed 5+ years, which is great. Finding tenants has never been a problem, if you can't rent it out in a month, price is too high.
I plan to expand to at least 10-15 rentals, that's where the real money is when you have enough to be bringing in a good income every month.
I would never own and rent commercial real estate of any kind unless the return was insane. Finding a tenant can be hard, i've moved yards a few times in the last few years and you see places up for 6-12 months. Companies can pull midnight moves or fold company leaving you high and dry a lot easier then when it's someone's house, or big damage if it's a building. You also run the risk of company going bankrupt and their crap sitting in your place for months while it's sorted out, and you don't get any rent, at least not here. I looked at buying land, it's cheaper to rent right now. I think there is a lot of guys who have owned the places for a long time and paid nothing, so it's easier to rent out for less then owning when it's free and clear, plus there is so much vacancy here.