@Zacharias0
I did the whole room mate thing for years and have one by one switched my three spare bedrooms to Airbnb. I have had some fantastic housemates who are still good friends and some I hope will be lifelong friends. There were others that were okay.
Then there were those that were just truly awful. Believe me, I have experienced almost everything with that lot, from an infestation of mice due to bad hygeine, to prostitutes and drug dealers being invited into my home, to sexual harrassment.
As @Paul154 says, often they come with a sense of entitlement that they are paying rent and can do whatever they like, including throwing a massive party without my permission. Enough. I learnt to make it clear that this is MY property, furnished with MY things. You follow MY rules or you get out. I am a live-in landlord and therefore the law is on MY side, not yours.
Unlike many hosts who have posted here, I am actually all for long-term guests (anywhere between one month and six month stays) and have changed my settings to attract them. My rooms are booked back to back and I have very high standards of presentation so constantly turning over three rooms whilst managing my job is just not feasible in the long run.
Also, my experiences of long-term guests have been really positive to date. They are like the most respectful, considerate housemates ever, only they pay considerably more! The thing to do is be really extra choosy about your long-term guests. I need to know a lot about them beforehand and they need to agree to a long list of very detailed rules.
I think I'm lucky also that my rooms seem to attract quite decent long-termers. They're not overpriced, but they're not the cheapest accommodation for a long-term stay either. It's a big investment, but the people who come here are willing to pay a bit more because they really want a nice place to stay and therefore they respect me and the house way more than your average housemate who is paying less.