The issue is if it never occurred to you that you might have been scammed you might not ever think to look.
I built my first computer last year, with all NiB internals, my main concerns when assembling it was does it work. If it underperformed (due to a bootleg part) I might not have been able to appreciate due to a lack of reference point.
This kind of practice is perfect for targeting the person using PC part picker to build a computer without an indepth knowledge or a relative buying it as a gift for someone else.