yep been there. get accused of cheating all the time XD back in MW3 i was playing Face off 2 v 2 by myself and wrecking these guys. Was using My MK14, now I can forgive them for thinking its modded. I really can, sometimes I have a hard time believing it isnt. So i can understand why they would. they accused me of modded at which point I told them to pick up my gun and try it themselves... to which they replied that they already had and couldnt do it XD best laugh i had all MW3.
next game, same guys (campity lil dudes) im not rushing in after them as my partner is worthless. So i wont act recklessly until I can figure out where they are. so i sat there on the hill chewing on the info I have gathered on these enemies and eventually came to the conclusion that the most likely spot that they enemy would be in was in the shed in a specific corner (various reasonings lead me to this) so, I just started blasting away at the wall. boyaa rewarded with a kill and a WALL HACKER! comment (actually just remembered... i made a short youtube video "how to sense your enemy")
im fond of telling people who accuse me of such things "YES! it is a mod! its the new bionic finger! i ordered it from japan last night (over night delivery) and was in the hospital early this morning as they attached it to my hand.... still hurts a bit... but this thing is awesome!" (every time i tell it, the location from where it came changes)