Facebook is going to spam your friends regardless of whether you "Like" anything. My policy right now is to "Like" things that I think are worthy of attention, and which I'm not embarrassed to be associated with. Not that Facebook will suggest them to anyone without getting paid, but I might as well help some good people get value for their advertising dollar.
It really does suck that Facebook is spamming our friends in our name, though. Perhaps you're right, and it's best not to "Like" anything, so my friends don't associate my name with the annoying intrusion of commercial messages into their news feed.
Nothing, which is why you might want to avoid the "Like" button. You can choose between not "Like"-ing anything, to avoid your name showing up on spam, or you can "Like" worthwhile, interesting things, so your friends' spam is marginally more interesting.
It really does suck that Facebook is spamming our friends in our name, though. Perhaps you're right, and it's best not to "Like" anything, so my friends don't associate my name with the annoying intrusion of commercial messages into their news feed.