From 1998 - 2004 I owned a house and rented out rooms to min. 3 and max 5 people. From 2004-2006 I lived in a house that my wife and I renovated & saved from being condemned due to health code violations.
1 We rented the extra rooms out to two people. We've also rented a room out in our current place since March of last year. We haven't had any really bad experiences, though I'd say our current housemate is more of an inconvenience than it's worth (owns a rabbit & the wife and I have allergies, is something of a slob, and is somewhat unpleasant though not totally intolerable to be around).
The obvious benefit of renting out rooms is that you generate some decent income with little to no effort. Also, if they're likeable people, you'll likely look forward to coming home to a non-empty house, and you'll get to spend more quality time with another/others than otherwise.
But there's a lot of potential for tension, awkwardness, and conflict...
- You'll sacrifice some privacy and immediate access to the household facilities (kitchen, bathroom(s), possibly television & computer if held in common, washer/dryer, etc.).
- They might have idiosyncracies that clash with your own. For instance, if you like things tidy at pretty much all times, it might growingly irritate you that your housemate is a bit more lax on, say, doing the dishes or folding up blankets in common areas.
- Additional shared expenses like groceries could be problematic if one of the parties tends to consume more than the other.
- Noise and having guests over might disturb your or another's peace.
- If they fail to pay their share of expenses within a reasonable time frame, this could lead to real tension.
Many of these things can be avoided, or at least mitigated, if you carefully screen your potential housemates carefully, talk out your expectations with them before they move in and continue to talk routinely while they're living there.
As far as screening is concerned, here's what we did: We started with considering close friends and family who could move in to our place and who needed a place to live. We identified their tendencies and imagined whether and to what extent we could tolerate them, and discussed how they might clash with our tendencies. We did the same with acquaintances, and then ranked them from most preferred to least preferred. I'm glad we've always settled on housemates from our pool of family, friends, and acquiantences, and never had to turn to advertising open rooms on craigslist or similar sites, as there's much more risk in that approach.
This isn't a foolproof method, of course. We're less than satisfied with our current housemate (though we acted in haste in this instance, since he was in need of assistance). His tendencies somewhat clash with ours even though it didn't seem that way before he moved in, and talking about our expectations hasn't really helped, either. But, all my/our other housemates were pretty pleasant to live with, and I/we've had 11 housemates, so that's a pretty good track record. If you're willing to give up some privacy, can tolerate minor inconveniences, and put in the work to find a compatible housemate, it'll certainly be good for you financially and likely will be an overall positive experience.
Let us know what you decide and how it goes!
1. Long story, but here's the shortened version: the house was owned by an older gentleman who didn't have the expertise, strength, or funding to fix the place up or pay someone to do it. Plus the guy made the people from that Horder's TV show look like a bunch of fucking amateurs - trash packed from floor to ceiling & wall to wall, with small canyons that allowed one to navigate from one room of junk to the next. I felt sorry for him, and agreed to help him out in exchange for my wife and I renting out the place at $100 a month + utilities (average of about $160 a month) while the guy lived in an apartment, which his veteran's assistance paid for in full. We rented out two of the rooms for $300 each, giving us a $340 monthly net profit.