Sean's house is a very good option for those who don't mind sharing a space with others. Keep in mind, though, that while the bedroom is private, locked, and VERY comfortable, you'll potentially be sharing kitchen and bathrooms with other guests, so a part of the cleaningness and comfort will depend on other people you won't know in advance. For our group, we had a wonderful time with the other guests, and everything was nice and clean.
One thing to note is that the neighborhood the house is located is quite suburban, and honestly the cars lying on sidewalks and the lots of trash on the streets caught us off guard. Knowing San Francisco better, I now can say this is quite common throughout the city, and safety isn't really an issue despite our initial impression. Have a look at the surroundings on Google Street View or the likes if you want to have a previous look at that.
We had a rental car, it was easy to find spots for parking during the day and early night, but at 1am (when we got there) it took as a while. We used public transportation to go to the center, which took us about 40min from the house's door.
Finally, I would really recommend the place, if you keep in mind everything pointed out. it's just a no fit for some kind of travelers.