I set up a fake Facebook profile a long time ago as a prank, added everyone at my college as friends, and people I know still say they get notifications about his birthday. And people still reach out to wish him a happy birthday.
I have no idea what credentials I used to create it so I can't delete it, but it still exists (unlike the person it's pretending to be).
I think the signature of those kinds of fake accounts are different than most of the malicious accounts though.
You creating a fake college account and forgetting about it probably passes as human enough, there's no concerted effort or agenda to that account besides existing and adding friends at your college.
I think what makes bots and fake accounts generally detectable is consistently pushing certain messages in ways that exceed normal human behavior, as well as showing patterns across many fake accounts.
It's hard to see a pattern in one fake account, but easy to spot it across many.
I have no idea what credentials I used to create it so I can't delete it, but it still exists (unlike the person it's pretending to be).