I think there's a difference of kind, and not degree, between the services that you use for financial gain, and the services you use because you like them. I can understand if you don't read Facebook's TOS. I haven't. But if I used Adwords, and I depended on it as a part of my business, I would read the TOS.
Yes, good advice. But you're likely to find some large grey areas, and also some things that the ToS seems to forbid but seem reasonable / ethical, and lots of people are doing. If you avoid all of those grey and pseudo-black areas, you're hamstringing yourself. If you don't avoid them, you're vulnerable to being shut down arbitrarily. Which path do you choose?