How to tell if someone is using a chess engine or not

      It is a peaceful day, you get on Chess.com and you match up with someone, you play and play and eventually he wins, you think nothing of it and go and analyze it, and you see an unusually high accuracy, 99.5. This is weird as you only have 200 rapid, how d you know if this is a chess engine?

     Chess engines have never been fun to play with, they just steal your ratings and run off with it, but sometimes even if they have a high accuracy that doesn't mean they used a engine. GM Hikaru usually gets a high accuracy but that doesn't mean he used a chess engine, lets dive deeper.

      I usually figure out if someone uses a engine if they use extremely good moves in a short amount of time. Great moves take time to think about. A chess engine calculates millions of moves per second, and almost never loses. When you get suspicious go to their profile, if the name is something like WASADCLUB69420LOSER then it's probably a engine user on a throwaway account. Now, click on to their archive. If the archive notes that they never lost, then its probably a engine user. Even most Grandmasters lose here from time to time. A fresh account is a red flag. Most people who make new accounts don't just come in and instantly start winning every game and making moves like idk QD5 and checkmate in less than 5 moves in 2000 rating places.