If you were to start a new game, and stocked it straight away, I bet you'll see your sims all over. Active sim's neighborhood has 3 empty houses-> fill houses-> homeless households already exist, use first. Active sim visits bar-> populate bar-> use these idle sims already existing.
I only tried stocking a game once, but it did work. Male played sim, added like 8 homeless girls from my library, and let's see who he happens to run into, and ends up liking, on his own. I saw those girls all over, and it was a matter of hours (game clock hours) before he was doing naughty mod things with one, without me doing anything to tell him to!