Insidious sandbagging (opening piece saccers):

I reported it and they never got busted, so apparently it's not very well enforced.

It is a form of cheating if someone is manipulating their rating. Sacrificing a piece early in the game to throw the game is sandbagging and this is a potentially ban-able offense. Just report it https://support.chess.com/article/209-how-do-i-report-someone and move on. Just because you don't see action taken, this doesn't mean nothing happened. chess.com typically issues warnings or temporary mutes; banning someone is reserved for more serious cases or repetitive offenders.
It is against chess.com tos to discuss cheating in the public forums though. You are free to share in this chess.com club though: https://www.chess.com/club/cheating-forum
What do you think of strong chess players that keep their rating low and intentionally sac a piece in the opening (usually Nxf7 for example) to see if they can outplay you (which usually they do)? IMO it should be something that can be reported for sandbagging, because it dupes you into playing someone far above your skill that you did want or expect to face, and it becomes very frustrating when they eventually win enough material back to gain a winning position. I want to face players my level, not some master posing at my level and then making me look like a fool for losing games a piece up. I've tried reporting it, but apparently this isn't considered a fair play violation.