Go over to friend's place and watch the ads they get, you'll get a good idea of what kind of health concerns or illnesses they may have.
So far, in situations where it wouldn't be rude to ask, I've been able to determine with pretty good accuracy that at least someone in the household has the advertised health concerns.
You can also get an idea of their financial situation, given what buckets advertisers put them in and what they're advertised, as well.
Similarly, advertisers know when you're at friend's location, or elsewhere, and may show ads tailored to your profile.
So far, in situations where it wouldn't be rude to ask, I've been able to determine with pretty good accuracy that at least someone in the household has the advertised health concerns.
You can also get an idea of their financial situation, given what buckets advertisers put them in and what they're advertised, as well.
Similarly, advertisers know when you're at friend's location, or elsewhere, and may show ads tailored to your profile.