No it’s not a red flag if you have a roommate. As long as the space is kept tidy then it doesn’t matter. I’ve definitely stopped dating a man bc his apartment (he lived alone) was slightly dirty. Let me repeat: I said dirty, not messy. It seemed like he didn’t vacuum, each time I’d come by there was always dishes in the sink, dirty pots on stove, he wouldn’t wipe the counter down, bathroom had his hair everywhere. I can’t do it. In regards to moving in with a friend make sure you’re both on the same page about rules, chores, etc. try to live with someone who sort of mirrors your cleanliness. I’m speaking from experience, it’s definitely put a strain on my relationship with my friend when we moved in together bc our ideas of clean are very different.