Buying equipment is more of a financial decision and not an ethical decision. Not everyone is committed to buying a $700 driver for casual golf. I’d even suggest that this not a whole lot different than the next ball in play is the last one found. Not my game, but it won’t impact me.

I won’t deal with eBay for golf equipment. Buying or selling. Selling is the worst. The buyer just wants to try the product and then insists the listing was incorrect and wants me to pay shipping to return it to me. And if I had a dime for every posting on the web or facebook “is this rea?”, I could have retired 2 years earlier. The price is the siren song.

Caveat emptor.

Maybe if they told me they got their driver by stealing it out of a golf bag at the club drop, then I probably would steer clear of them for future rounds. I don’t normally preach morality to fellow golfers but many factors do go into who I like to pair up with on the golf course. I can’t imagine the conversation of buying counterfeit would come up in my foursomes. I’m a guy who likes to play with minimal conversations. Not a knock on my fellow extroverts, I’m just a Cam Young kind of golfer.

Golf is an expensive sport. I don't criticize someone for trying to save a few bucks on equipment. I have bought a few things on ebay, but only from golf equipment suppliers I recognize, and only specific things I am looking for. None of those purchases can really be called a great deal. Not uncommon for somebody looking for a specific model head, shaft, etc that is no longer manufactured to turn to ebay in hopes of finding it.
To answer your question, if they're enjoyable to play a round of golf with, I don't care where they bought their equipment or how much it cost them. For me golf is complicated enough that my focus is limited to my game. But I must admit that if they are bragging about the great deal they made on a club, and they shank it into the woods, most likely I am going to razz them about it.