Search Engine Optimisation can be the ethical way or ‘spammy’ way. Even large corporations often don’t care, as long as they get their rankings up:

Over the last few months, I’ve seen GoDaddy rise up in the rankings for a lot of hosting related terms. At first I suspected they were finally using their very strong domain in a smart way, but then I noticed they ranked for terms I know you can’t rank for without a lot of external links, no matter how strong your domain. Let me tell you how I figured out that they got those external links by embedding links in their clients websites.

via GoDaddy’s spammy link building techniques • Yoast