For one we had a service that records video of your site visit so we knew exactly how you interacted with it. It would be no different from be standing behind you and watching your screen as you navigated a website. While the data is anonymised, I'm still morally against essentially video recording someones interactions with a site. There was never any notice that they were being recorded.
The email marketing workflows were relentless, especially on e-commerce stores that required several points of contact in order to make a purchase. We were able to build profiles on most customers by combining purchase history, personal details, and details pulled from social media to get a fairly accurate portrait of someones behaviour. For example, if someone bought engine oil, we knew that a typical bottle of engine oil would last someone, say, 6 months. The email marketing workflow would automatically send out a promotional coupon 6 months later for a discount on more engine oil. But because we were able to build profiles on people, we were able to tell that "Joe Blogs" is a motoring enthusiast and therefore the likelihood of him using up that engine oil in three months rather than six months increases by 50%, so send out the marketing materials to him quicker than the regular customers. There were very smart people working on these campaigns. Statisticians, psychologists, linguists and the like.
Because we had several points of contact with customers, having them unsubscribe from an email list wasn't bad. If you unsubscribed from the email, you would just be sent SMS notifications. If you replied STOP to that, you were sent physical mail, and after all that it was still quite easy to target you with remarking ad campaigns.
The amount of complete and utter garbage we were pouring out onto the web on a daily basis was staggering. Hundreds of pages a day that were of absolutely no use to anyone but to Google would mean that we were able to rank clients for some very serious keywords where real people needed real help but were instead being presented with crap that we'd put out that wasn't meant to actually help anyone but to get the #1 position and the sell things. And when I mean people who need help, I mean people who seriously need help. We'd push crap to rank for things like depression, bankruptcy, divorce, a whole array of legal issues.
I hated working there.