It's an investment. Every investment has a risk. It's your responsibility to find ways to mitigate this risk, like renting to someone you know or having a modest price to someone who can pay afford it vastly, no to anyone that looks the cheapest rent.

That's why people sing contracts of X years, and asks for employment contracts and a minimum quantity of money in the bank. In this situations you can still get it wrong, but that's investing, it's always risky.