Recently, I purchased a ticket to a concert on Eventbrite. Here is the order confirmation page: 

I was not pleased to find the following message on the order confirmation page:

By purchasing a ticket, you will also receive weekly email blasts from Ruby Skye about upcoming events, guest lists and more.

The reason why this message irked me is because it was never shown at any point prior in the purchase flow. The user was never properly warned that a purchase would result in this added consequence of having their email added to a mailing list. Sure, at the end of the day, it’s not a huge deal and I can eventually get out of it with a simple unsubscribe. But that’s a waste of the user’s time — not to mention that this technique of acquiring emails is dishonest and not customer centric.