It's usually a cheater. If it's a short game, probably not. But if it's a game 40 moves long, very suspicious.
99.4% accuracy for 500 rating

If he memorized gambit and you fell for it, probably not a cheater. If it was a game that lasted for several moves he probably cheated.

Everyone can have a good game sometimes without cheating.he probably didnt cheat.if it was a short game its easier to get as high accuracys as that.

If your accuracy is low, it may be that the best moves for your opponent are easy to find, even for a ~500 (such as taking a hanging piece or finding a simple fork).

Your opponent didnt cheat.you played very badly and defended badly and your opponent easily took advantage of that.a 1300 would be able to play as well that game without it being super difficult to play with 99.4 accuracy like it in normal games is

Your opponent didnt cheat.you played very badly and defended badly and your opponent easily took advantage of that.a 1300 would be able to play as well that game without it being super difficult to play with 99.4 accuracy like it in normal games is
He has a suspiciously high number of games at 90+ for a 500 though. Definitely suspicious. 500 rated players should not find all the best moves in a game, even if it's 20 to 30 moves.
Joined Chess.com for 6 weeks and got 500 in rapid, I'm happy with that.
I just lost a game to another 500 rating player. Losing is fine; I got 73%, it reflects my strength. But my opponent has an accuracy of 99.4%. How's that possible for a 500 player attaining that level?
Intriguing.