Good points by Cliff and Scott. I can't begin to convey all the $3,000 bills (and worse) from bad renters. It's very frustrating when they're destroying your property and it takes almost a year to get them out when you go through the "legal channels" to have them evicted. Bad renters know the system and rely on it.
Most all landlords try the "take the doors off" trick or "shut the power and water off" trick, and that just gets them in trouble. It's illegal.
I used subtle persuasion. I waited till they left and moved all their things to storage. It was a simple process. They always called the police and they'd come talk to me. I'd explain that they hadn't paid rent in months (which was ALWAYS the case) and that I'd tried to contact them dozens of times (also true) and assumed they'd abandoned the property based on the condition of the living quarters. All I had to do is show them and they immediately took my side and asked me to return their items. I'd explain that all they had to do was go to the storage facility and pay the bill and they could retrieve their personal effects.
It never failed. It wasn't my idea, either. A good friend of mine who had a number of rentals gave me the idea. It saved me a fortune.
When keeping security deposits in these instances, it's law to send a letter to the renter outlining the conditions why you've kept it. It's a good idea to add in all the other costs incurred and to send it certified. If you don't, they can take you to court, sue for their deposit, and you'll have to pay them double plus court costs. If you arrive at court with the returned certified letter (that you sent to their address at your property because they never leave a forwarding address with the PO) the case is over before it starts.
Those are just a couple horror stories I thought of. There's lots more.
If rental properties are personal, it's not something to get into. Things like renting your current home, or the home you've lived in for years, or the family homestead, things like that.
If there's emotional attachment, it'll drive a person mental. If it's just a business, not so much. It's still tough, though. It's not for the faint-hearted.