Take a close look at the link to Slot Play Coupons tslate provided and you'll notice it contains "id=26714". This is tslate's i.d. number with Slot Play Coupons so when you order using that link, he/she gets whatever commission they give their "affiliates" for sending them buyers.
More advanced affiliate marketers often "mask" the affiliate code in their links. That way the links they thoughtfully include in posts announcing "deals" don't betray the fact that their actual goal is to profit from their readers.
Ethically I think all "affillate" posters, bloggers, reviewers, etc. should disclose up front that they'll profit if you buy something using links they provide. That kind of honesty doesn't diminish their credibility, it enhances it. Just my opinion.