Someone already explained how the hot spot thingworks.
One thing that personally bothers me is why people assume everyone should talk and be social when you are visiting in a sim. Sometimes I am in multiple conversations through IM and a stranger approaches, ten if you don't answer them back they get pissed. In some other occasions I have visited romance sims with female friends, and even if we are alone in a spot someone suddeny runs/flies towards us trying to engage a conversation. Common, you don't even do that in RL if you see a couple alone!
But yeah is my rant You can always check the person's profile first, some state that they like to be alone or don't like be approached by strangers