If you're renting out your spare room 70-100% of the time, why don't you just get a roommate? Seems like it would be safer, less work, and you'd ideally have a better long term relationship.
Well, we like meeting new people, we probably would have to charge the roommate less and there are different social obligations for a roommate. (For example a guest that stays for a few days is unlikely to leave a mess in the kitchen). In addition any little annoying habits don't have enough time to become tiresome.
Lastly, we can have the room available for our friends and family when they come and visit (which is the point of having a guest room in the first place). My parent stay there (for free, of course) about 2 nights a month.
Well, to look at it from solely a financial point of view, a room in an apartment is worth much more if you rent it out by the night or week rather than by the year (like you would with a roommate).
Here in my neighborhood, in Chicago, one can find a room for about $40/night; 15 nights and I already have half my rent. So yes, having a roommate might be less work (but that depends on what you consider "work") but I can make more money renting a room out by the night.
