We've all had that nightmare flatmate. The one who doesn't clean, or who always eats your food, or who leaves passive aggressive notes on the counter... the list goes on.
Thankfully, you'd assume the worst offenders have either learnt their lesson by now or are continuing to flat with a bunch of uni students who think the electricity being cut off is romantic.
Because while the benefits of house sharing remain the same regardless of age (split responsibilities and finances, anyone?) the etiquette deemed acceptable does not.
"Sharing is hard. I think anyone who has lived with a flatmate for longer than two years is doing really well," founder of The Good Manners Company, Anna Musson, told The Huffington Post Australia. "But things do change depending on what age you are.
"In your 20s, often a main focus is budget. You're discussing things like splitting the bills, friends staying over, cleaning, sharing clothes... I remember I had a flatmate who would wear my clothes, even my underwear. Some people think that sort of behaviour is fine but for others it really crosses the boundaries.
"By the time you get into your 30s, there tends to be more disposable income between you. Things worth discussing are whether or not you're going to pay for a cleaner and how often, as well as the frequency of partners staying over."
Musson also points out the number of people living in the one house generally decreases the more disposable income is available (so you can finally bid farewell to flatting with six other people and a partridge in a pear tree.) However, this can also bring new issues to the surface, such as a certain 'responsibility' to be home at least some of the time.
"If it's, say, just the two of you, a flatmate can become lonely and resentful if you are never home," Musson said. "Of course, if there is five or six of you, someone who is never home is a blessing, but this is pretty rare [for people in their 30s]."
For those establishing a new house sharing agreement, Musson says it's important to remember that your way isn't necessarily the way.
"This is a double edged sword. I find those who continue to share with people do tend to develop a certain flexibility. I think you'll find people who have been sharing for a long time have developed some flexibility with the ways things are done," Musson said.
"However, if living with someone else is driving you crazy, it might be better to move out on your own. Of course the downside of this is you will likely become even more set in your ways than ever. This is when it can become problematic."
At the end of the day, Musson says picking the right flatmate -- no matter what age -- all comes down to research and asking the tough questions early on, ideally before a person actually moves in.
"The number one rule is do your research. While it might be uncomfortable to ask certain questions that can seem personal, these are the things that could potentially undo the relationship later on," she said.
"For instance, if you are always freezing cold, there's no point in living with someone who will balk at the expenses of running a heater.
"Ask if they are allergic to anything, if they smoke, how they feel about drugs, how they feel about certain routines. When it comes to sharing a house, just getting along with someone just isn’t enough."
Of course, what a lot of people forget is they aren't perfect, either. But, for the sake of keeping everyone sane, Musson says there are a few golden rules everyone in a share house should try to follow.
"The first is clean up after yourself," Musson said. " Don’t just assume your boyfriend and girlfriend can stay over every night.
"Don’t smoke inside. And try to have a generous attitude.
"If you feel like you are the only one putting the bins out on a Friday night, remember some things just aren’t worth fighting about. Pick your battles.
"There are always going to be deal breakers, but it's not worth making a fuss over the things we don’t mind so much about."