Two of the guys I work with have buy-to-let properties on the same estate they've been renting out to students (and in one case a visiting lecturer) and haven't had any serious issues. Worst I recall him mentioning recently was a family he rented to who dried their washing indoors on racks but neglected to open windows so got the house mouldy.
I thought about renting my flat out when I moved several years ago, and I had the same fears about non-paying tenants and squatters, but apparently the law has changed a bit so evicting non-paying tenants is now a lot easier and cheaper. I had decided to go with a local agent who did a fixed fee cover everything deal - including paying you if the flat was unoccupied due to lack of tenants and legal fees etc if required.
In the end I sold the flat to one of those buy-it-quick outfits for a cut price and used the money to pay a huge chunk of the mortgage on my new house.