But, I don't get the ads for the roommates and the person basically will let you pay half of their rent and that's it. I also love the ones that are like "You have full use of the kitchen, but you can't use the stove or cook meat because I'm a vegetarian. But, it's totally cool if you aren't." Moving into someone's existing apartment can be difficult. Many times, the person you are moving in with can tend to treat you like a guest, rather than a co-inhabitant. If you find yourself in such a case, you basically have to assert yourself and say that you're not a guest--you pay rent, this is your home, etc.
That said, if you can tell that there will be red flags from the ad, it's probably best just to not even put yourself in that situation.
"You travel alone because other people are only there to remind you how much that hook hurts that we all bit down on. Wait for that one day we can bite free and get back out there in space where we belong, sail back over water, over skies, into space, the hook finally out of our mouths and we wander back out there in space spawning to other planets never to return hurrah to earth and we'll look back and can't even see these lives here anymore. Only the taste of blood to remind us we ever existed. The earth is small. We're gone. We're dead. We're safe."
-John Guare, Landscape of the Body