Is it unethical if I keep track of how many people buy which hats, so I know which kinds of hats sell best?

What about if I keep track of what hats each of my customers buys, so that I can tell which hats I might want to bundle together into hat packs?

Maybe I’m not super technical, so I pay a 3rd party service to analyze my transaction logs and tell me the above answers.

Or I realize some hats aren’t selling, so I check to see if people are going to that page and just not purchasing, or never going to that hat’s page at all.

To say that sites use tracking to “manipulate” users is playing pretty icky word games. Yes. The purpose of all marketing is to “manipulate”. So are opinion columns in newspapers. Job interviews are an employer manipulating a candidate and a candidate manipulating an employer. Manipulation is just a scarier-sounding word for “persuasion”.