Staying in Chungking Mansions is a unique Hong Kong experience, if not a bit claustrophobic due to the lifts and the smallness of the rooms. Although there are a lot of "seedy" lodgings there, there are a surprisingly large number of legit and clean guesthouses there, albeit a bit small.

I stayed at one guesthouse once in a room that was slightly bigger than a full size bed and the hallway shower was the size of a phone booth. Since all I could do there is STAND and kinda turn around, I wound up taking showers at the California Fitness across the street. Another time, I had a properly sized room with full size bed and ensuite bathroom. So YMMV there, but it's definitely something to check out, especially if you're part of the backpacker set. You definitely can't beat the location. Also, when I used to go there, the currency exchange stalls there had pretty good rates. ^

The last time I stayed at a guesthouse in HK was Noble Hostel over in Causeway Bay. A touch more expensive but much roomier and cleaner. Better neighborhood too!