It was an example. I do not add them anymore. But I get constant notices of random spammers adding me. And these notices show up on every Google page, including normal searches. There is no way Google can tell Mr. X is a friend of a friend or a random social spammer.
Even if you do the right thing, you get those notices. And even if only some of your friends fall for it, it spreads. And I don't blame them, it's a hassle to check.
Edit: and of course, I am not publicly listed! But they can bypass that by adding friends who have their list of contacts public (a default!)
Don't add anyone you don't know. Or, if they 'seem' interesting, banish them to a dark circle that you visit perhaps once in a few weeks.