My experience is limited to renting our house to which I intended to return. In one case it worked out really well. I could not have asked for a better tenant. The second time I did it, it did not work our nearly as well.
With the first house, I had great property manager, which is crucial for success. I would never even consider doing this without a property manager in the local area to the house. I simply could not have managed the property while posted elsewhere. As it turned out, I never did return to that house and still haven't gotten back to that city and here we are 20 years later.... I eventually sold that house after seven years for a tidy profit.
The second experience did not work out so well. I was out of the country for three years and unfortunately, the timing of my posting was such that the house didn't go on the market until the worst possible time (August) and it sat empty for nine months. The first set of tenants were students who damaged the hot tub ($2000 to repair) and the stove ($600 to replace). Then then tried to skip out on the last month's rent (I won that one). There was other damage to the house, but I could not determine whether it was the first or second tenants (the second "family" were no winners either). Long story short, when we re-occupied the house, we had to re-paint the living room and dining room and repair some walls and other things. Nothing too serious (although there is still that mystery burn mark on the living room hardwood) and we've mostly recovered (repairs are also tax-deductible). I think the biggest disappointment was with the property manager. They worked very hard in some aspects, but fell short overall. My mistake in this case was to hire a real estate agent to manage the property vice a property management company. My small consolation, is that mail from various collection agencies, looking for all the tenants, still arrives from time to time. The phone calls were fun too as I happily threw the tenants under the bus. The funniest part was when I got an email from one tenant asking for a receipt for the rent they had paid (presumably for tax purposes). I happily agreed, as soon as she remitted the balance owing for the damages. ;D She hasn't gotten back to me.... Unfortunately, you cannot ask for a damage deposit in Ontario.
I have a friend who rents out a property on the other side of the country as an investment. Even when co-located with it, he crammed his family into a PMQ (with all that entails). Now that he's located here, he continues to rent it out. He's been fairly lucky with the property itself, but it's not without its headaches. Furthermore, the idea of owning a house that I'm not living in, while living in a PMQ has no appeal to me whatsoever. I don't enjoy being a landlord and the ONLY reason I did it was to be able to keep the house with the idea of someday returning to it. In my particular neighbourhood right now, there is a strong possibility that I if I sold my house and went away for a few years, I wouldn't be able to buy again in this area when I got back.
There are lots of people in the Regular Force who own multiple properties as investments and some are doing quite well at it, but it takes organization and if you're not co-located with them, a good property manager (which cuts into the profits even though the expense is tax-deductible). It's not for me though. Another thing to consider is that even you don't have tenants or your tenants aren't paying their rent, you still have to make your obligations. I remember being annoyed with a subordinate once who owned several properties and was living in a PMQ, yet was crying financial hardship (and looking for assistance).